🧅🍔 Onion Smash Burgers

Onion Smash Burgers are a classic diner-style burger made with a thin, crispy-edged beef patty smashed directly onto a hot griddle with thinly sliced onions. The onions caramelize into the beef, creating a juicy, savory burger with incredible flavor and texture.

Prep Time

• Prep: 10 minutes
• Cook: 15 minutes
• Total: About 25 minutes

Servings

4 burgers

Ingredients

Burger Patties

• 1½ lbs ground beef (80/20 recommended)
• 1 large onion, very thinly sliced
• 1½ teaspoons kosher salt
• 1 teaspoon black pepper
• 1 teaspoon garlic powder
• 8 slices American cheese (or cheddar)
• 4 hamburger buns

Burger Sauce (Optional)

• ½ cup mayonnaise
• 2 tablespoons ketchup
• 1 tablespoon yellow mustard
• 1 tablespoon pickle relish
• ½ teaspoon garlic powder

Toppings

• Pickles
• Lettuce
• Tomato slices
• Extra onions
• Jalapeños (optional)

Instructions

1. Prepare the Onions

1. Slice onion very thinly using a knife or mandoline.
2. Keep slices loose so they cook evenly.

2. Make the Sauce

1. Mix mayonnaise, ketchup, mustard, relish, and garlic powder.
2. Refrigerate until ready to use.

3. Smash the Burgers

1. Heat a cast-iron skillet or griddle until very hot.
2. Divide beef into 4 loose balls (do not overwork).
3. Place beef balls on the hot surface.
4. Immediately cover each with a handful of sliced onions.
5. Smash firmly with a spatula until very thin.
6. Season with salt, pepper, and garlic powder.

4. Cook Until Crispy

1. Cook for 2–3 minutes until the edges are browned and crispy.
2. Scrape underneath with a spatula and flip.
3. Add cheese.
4. Cook another 1–2 minutes until melted.

5. Assemble

1. Toast buns with butter if desired.
2. Spread sauce on buns.
3. Add onion smash patty.
4. Add pickles and toppings.
5. Serve immediately.

Serving Suggestions

• 🍟 Crispy fries
• 🧅 Onion rings
• 🥤 Milkshake
• 🥒 Dill pickles

Variations

🧀 Double Onion Smash Burger

Stack:

• Two thin patties
• Extra caramelized onions
• Double cheese

🌶 Spicy Smash Burger

Add:

• Pepper jack cheese
• Jalapeños
• Spicy burger sauce

🥓 Bacon Onion Smash Burger

Add:

• Crispy bacon
• BBQ sauce

Tips for the Perfect Smash Burger

• Use 80/20 ground beef for juicy patties.
• Smash only once—don’t press again while cooking or juices escape.
• A very hot cooking surface creates the signature crispy crust.
• Use a sturdy spatula for the best smash and flip. 🍔✨