Crispy Onion Chicken Sandwich

Featured in: Simple Suppers

This mouthwatering sandwich combines juicy, buttermilk-marinated fried chicken thighs with golden crispy fried onions and silky garlic aioli on a soft brioche bun. The chicken is marinated for at least 30 minutes to ensure maximum tenderness and flavor, then dredged in a seasoned flour and cornstarch mixture for extra crunch. Thin-sliced onions are fried separately until golden and crispy, adding a delightful textural contrast. The garlic aioli brings creamy richness to balance the crispy elements. Assembly takes just minutes—spread aioli on toasted buns, layer with lettuce if desired, top with fried chicken, and crown with a generous mound of crispy onions. Perfect for a satisfying main course that serves four.

Updated on Sun, 18 Jan 2026 08:46:00 GMT
Golden-brown fried chicken thighs piled high on a toasted brioche bun, topped with crispy fried onions and creamy aioli, ready to serve. Save
Golden-brown fried chicken thighs piled high on a toasted brioche bun, topped with crispy fried onions and creamy aioli, ready to serve. | butterhollow.com

The sound of oil crackling always makes me think of lazy Sunday afternoons when I have nowhere to be and plenty of time to fry things properly. This sandwich came together one weekend when I had leftover buttermilk and a craving for something indulgent. I piled on way too many fried onions the first time, but honestly, that's become the whole point. Now I make extra onions just so I can snack on them while I cook. It's messy, it's rich, and it's worth every single napkin.

I made these for a group of friends during a game night, and the kitchen got so loud with everyone hovering around waiting for the next batch. Someone suggested we skip the buns and just eat the chicken with our hands, which we did for about two pieces before realizing the aioli situation required bread. We ended up assembling them assembly-line style, each person adding their own amount of onions. One friend made hers with nearly no onions, another built a tower I wasn't sure would fit in his mouth. Both were right.

Ingredients

  • Boneless, skinless chicken thighs: Thighs stay juicy and forgiving, even if you fry them a minute too long, and their flavor is richer than breasts.
  • Buttermilk: This is what makes the chicken tender and gives the crust something to cling to, so don't skip the soak.
  • Garlic powder and paprika: These season the marinade from the inside out, building flavor before the breading even happens.
  • All-purpose flour and cornstarch: The cornstarch makes the crust extra crispy and light instead of heavy and doughy.
  • Smoked paprika: Adds a subtle smokiness to the breading that makes people ask what your secret is.
  • Yellow onion: Slice it thin so it fries up shatteringly crisp and sweet, not chewy.
  • Mayonnaise: The base of the aioli, creamy and rich enough to hold up against all that crunch.
  • Garlic clove: Fresh garlic in the aioli is sharper and brighter than powder, worth the extra minute of mincing.
  • Lemon juice: Brightens the aioli and keeps it from feeling too heavy on the sandwich.
  • Dijon mustard: Just a touch adds tang and depth without making the aioli taste like mustard.
  • Brioche buns: Soft, slightly sweet, and sturdy enough to hold everything without falling apart in your hands.
  • Vegetable oil: Use something neutral with a high smoke point so the flavor stays clean and the frying stays safe.

Instructions

Marinate the chicken:
Whisk the buttermilk with garlic powder, paprika, salt, and pepper until smooth, then add the chicken thighs and turn them until every inch is coated. Cover the bowl and let it sit in the fridge for at least 30 minutes, though a few hours makes them even more tender.
Prepare the breading:
In a shallow dish, combine the flour, cornstarch, smoked paprika, salt, and pepper, mixing well so the spices distribute evenly. This is your armor for the chicken, so make sure it's well seasoned.
Coat the onions:
Toss the thinly sliced onions in flour, salt, and pepper until each piece is lightly dusted. Shake off any excess so they fry up crisp, not clumpy.
Fry the onions:
Heat about an inch of oil in a large skillet to 350°F, then fry the onions in small batches for 2 to 3 minutes until they turn golden and crispy. Drain them on paper towels and resist the urge to eat them all before assembly.
Bread the chicken:
Pull each thigh from the marinade and let the excess buttermilk drip off, then press it firmly into the breading mixture on both sides. Make sure the coating sticks well so it doesn't slide off in the oil.
Fry the chicken:
Carefully lay each breaded thigh into the hot oil and fry for 5 to 7 minutes per side, flipping once, until the crust is deeply golden and the internal temperature hits 165°F. Transfer to a wire rack so the bottom stays crispy.
Make the aioli:
Stir together the mayonnaise, minced garlic, lemon juice, Dijon, salt, and pepper in a small bowl until smooth. Taste it and adjust the seasoning if needed.
Toast the buns:
If you want a little extra texture, butter the cut sides of the brioche buns and toast them in a skillet until golden. This step is optional but makes a difference.
Build the sandwich:
Spread aioli generously on both halves of each bun, then layer with lettuce if using, a fried chicken thigh, a big pile of crispy onions, and the top bun. Press down gently and brace yourself.
A close-up of the Crispy Onion Chicken Sandwich showing juicy buttermilk chicken, crunchy onion strings, and melted butter on the soft bun. Save
A close-up of the Crispy Onion Chicken Sandwich showing juicy buttermilk chicken, crunchy onion strings, and melted butter on the soft bun. | butterhollow.com

There was a night when I made this for my brother after he had a rough week, and he didn't say much while he ate, just kept nodding and reaching for more napkins. When he finished, he looked at me and said it was exactly what he needed. I didn't realize until then how much comfort can fit inside a sandwich. It's not fancy, but it's generous, and sometimes that's the same thing.

Storing and Reheating

Fried chicken is always best fresh, but leftovers can be stored in an airtight container in the fridge for up to two days. Reheat the chicken in a 375°F oven for about 10 minutes to bring back some of the crispness, and make fresh onions if you can since they don't reheat well. The aioli keeps for up to a week in the fridge, so you can make it ahead if you're planning for a busy day. I don't recommend freezing the assembled sandwich, but uncooked marinated chicken freezes beautifully for up to three months.

Customizing Your Sandwich

This sandwich is forgiving and loves variation, so don't be afraid to make it your own. Add pickles for tang, hot sauce for heat, or a slice of cheese if you want it even richer. I've used chicken breasts when thighs weren't available, just watch the cooking time since they dry out faster. Some people love adding coleslaw for crunch and freshness, and honestly, it's a great move. You can also swap the brioche for a potato bun or even a sturdy ciabatta if that's what you have.

Serving Suggestions

This sandwich is filling enough to stand on its own, but it pairs beautifully with crispy fries, sweet potato wedges, or a simple green salad to balance the richness. I like serving it with cold beer or iced tea, something refreshing to cut through all that fried goodness. If you're feeding a crowd, set up a topping bar with extra aioli, pickles, hot sauce, and onions so everyone can build their perfect version.

  • Serve with a tangy pickle spear on the side for contrast.
  • Pair with crispy fries or a light cucumber salad.
  • Offer extra aioli and hot sauce for those who want more.
Homemade Crispy Onion Chicken Sandwich stacked with lettuce, golden fried chicken, and a generous layer of crispy onions on a brioche bun. Save
Homemade Crispy Onion Chicken Sandwich stacked with lettuce, golden fried chicken, and a generous layer of crispy onions on a brioche bun. | butterhollow.com

This sandwich doesn't need a special occasion, it makes regular days feel a little less regular. I hope your kitchen smells as good as mine does when this comes together.

Kitchen Tips & Answers

How long should I marinate the chicken?

Marinate the chicken in buttermilk for at least 30 minutes, though up to 4 hours is ideal for deeper flavor penetration and improved tenderness.

Can I use chicken breasts instead of thighs?

Yes, you can substitute chicken breasts for thighs. However, reduce the frying time to 4-6 minutes per side to prevent drying out, as breasts are leaner than thighs.

What temperature should the oil be for frying?

Heat the oil to 350°F (175°C) for both the onions and chicken. Use a thermometer to maintain consistent temperature throughout cooking for even browning and proper doneness.

How do I keep the onions crispy after frying?

Drain the fried onions immediately on paper towels after frying. Store them in an airtight container at room temperature for up to 4 hours. Add them to the sandwich just before serving to maintain maximum crispness.

Can I make the aioli ahead of time?

Yes, prepare the aioli up to 24 hours in advance. Store it in an airtight container in the refrigerator. Stir well before using, and adjust seasoning if needed.

What sides pair well with this sandwich?

Serve with pickles, coleslaw, or crispy fries for added crunch and freshness. A cold beverage like iced tea or a cold brew complements the rich, crispy flavors beautifully.

Crispy Onion Chicken Sandwich

Buttermilk-marinated fried chicken with crispy onions and garlic aioli on a soft brioche bun.

Prep duration
25 min
Heat duration
25 min
Complete duration
50 min
Created by Ella Thompson


Skill level Medium

Heritage American

Output 4 Portions

Eating preferences None specified

What you'll need

Chicken & Marinade

01 4 boneless, skinless chicken thighs
02 1 cup buttermilk
03 1 teaspoon garlic powder
04 1 teaspoon paprika
05 ½ teaspoon salt
06 ½ teaspoon black pepper

Breading

01 1 cup all-purpose flour
02 ½ cup cornstarch
03 1 teaspoon smoked paprika
04 1 teaspoon salt
05 ½ teaspoon ground black pepper

Crispy Onions

01 1 large yellow onion, thinly sliced
02 ½ cup all-purpose flour
03 ½ teaspoon salt
04 ½ teaspoon black pepper
05 Vegetable oil for frying

Aioli

01 ½ cup mayonnaise
02 1 large garlic clove, minced
03 1 tablespoon lemon juice
04 ½ teaspoon Dijon mustard
05 Salt and pepper to taste

Assembly

01 4 brioche buns, sliced
02 Butter for toasting buns (optional)
03 Lettuce leaves (optional)

Method

Phase 01

Prepare Marinade: In a mixing bowl, whisk together buttermilk, garlic powder, paprika, salt, and black pepper. Submerge chicken thighs ensuring complete coverage. Cover and refrigerate for at least 30 minutes, up to 4 hours.

Phase 02

Mix Breading Mixture: In a shallow dish, combine flour, cornstarch, smoked paprika, salt, and black pepper. Set aside.

Phase 03

Coat Onions: In a separate bowl, toss sliced onions with flour, salt, and black pepper until evenly coated.

Phase 04

Fry Onions: Heat 1 inch of vegetable oil in a large skillet to 350°F. Working in batches, fry onions for 2-3 minutes until golden and crispy. Drain on paper towels.

Phase 05

Bread Chicken: Remove chicken from marinade and allow excess buttermilk to drip off. Dredge each thigh thoroughly in the breading mixture, pressing firmly to ensure adhesion.

Phase 06

Fry Chicken: Fry chicken in the same hot oil for 5-7 minutes per side until internal temperature reaches 165°F and exterior is golden brown. Transfer to a wire rack or paper towels to drain.

Phase 07

Make Aioli: In a small bowl, whisk together mayonnaise, minced garlic, lemon juice, Dijon mustard, salt, and pepper until smooth.

Phase 08

Toast Buns: Optional: Butter brioche buns and toast in a skillet over medium heat until golden on both sides.

Phase 09

Assemble Sandwich: Spread aioli on both cut sides of each bun. Layer with lettuce if desired, followed by fried chicken thigh, and a generous portion of crispy onions. Top with bun half and serve immediately.

Kitchen tools needed

  • Mixing bowls
  • Large skillet or deep fryer
  • Kitchen tongs
  • Wire rack or paper towels
  • Chef's knife and cutting board
  • Shallow dish for breading
  • Whisk
  • Instant-read thermometer

Allergy details

Always review individual ingredients for potential allergens and seek professional medical guidance if uncertain.
  • Contains eggs (mayonnaise)
  • Contains wheat (flour and brioche buns)
  • Contains milk (buttermilk and butter)
  • Contains mustard (Dijon in aioli)
  • Brioche buns may contain soy or additional allergens—verify packaging

Nutrient breakdown per portion

Numbers shown are estimates only - consult healthcare providers for specific advice.
  • Energy: 670
  • Fats: 32 g
  • Carbohydrates: 61 g
  • Proteins: 32 g