Caramelized Onion Burger – a next level smash burger!
There’s nothing better than a smashburger with melty cheese, caramelized onions, and a big swipe of special sauce. This caramelized onion burger is messy in all the right ways – a thin, craggy patty, jammy onions, buttery brioche, and an extra large dollop of sauce that drips down your wrist (the sign of a truly next level burger situation).
Erica’s Thoughts
I love a good burger. But, I never made them at home on the reg. Homemade burgers were not in my weeknight dinner repertoire. And then I started smashing them. And everything changed. A burger is fine, but a smash burger. Please. Incredible.
Here are my hot takes on this delicious burger recipe:
- a super thin, craggy, caramelized patty that’s reinforced with a flavorful butter mixture means no bland, dry hunk of ground beef.
- there must be a good sauce or aioli situation – the special sauce here is a pretty typical mixture of mayo, ketchup, worcestershire and garlic and it’s soooo good.
- the lettuce should be shredded. shredded lettuce > piece of lettuce
- dill pickle chips for days. If you’re a butter pickle girlie I will judge you, but also you do you.
- oh, and a regular hamburger my girls shall not eat. But a smash burger? They go wild for. I can’t make it make sense; it just is what it is.
Smash a ball of beef on a ripping hot grill, watch the edges crisp into golden lace, then drape it with gooey cheese. Add in buttery toasted brioche and an extra special sauce and muah! From weeknight dinner to backyard cookouts to casual dinner party, these smash burgers are simple, versatile and so, so good.
What You’ll Need to Make Caramelized Onion Burgers
Ground beef: 80/20 is my go-to for juicy, flavorful burgers.
Butter + Worcestershire + Smoked Paprika: This trio gets mixed into the patties for rich, savory flavor.
Kosher salt: For that final smash-burger seasoning on the hot griddle.
Sweet onions: Sweet vidalia onions are the best but you could also use yellow onions or white onions.
Avocado oil + butter: Butter for flavor and avocado oil because it has a higher smoke point than butter.
Brown sugar + balsamic vinegar: These two ingredients aid in the caramelization process and enhance the natural sweetness of the onions.
Brioche buns: I love getting brioche buns from the bakery section of the grocery store instead of the bread aisle.
American cheese: The ultimate melty burger cheese.
Toppings: Tomatoes, shredded lettuce, pickles, crispy bacon, jalapeños maybe? Choose your journey here.
Special Sauce: Mayo, ketchup, horseradish, Worcestershire, mustard, garlic, smoked paprika, hot sauce combine to make a creamy, punchy burger sauce. You probably have many of these simple ingredients in your fridge/pantry already.
How to Make this Caramelized Onion Burger Recipe
Prep the patties
Melt butter and whisk in the Worcestershire and smoked paprika. Place beef in a large mixing bowl and pour the butter mixture over the beef. Use your hands to mix until evenly combined and shape into four balls.
Caramelize the onions
On a flat top grill or large skillet, heat oil and butter over medium-low heat. Add thinly sliced onions and toss until well-coated in fat. Stir in brown sugar, balsamic, and salt. Keep it low and slow until they’re golden brown and jammy (20-25 minutes total).
Smash the patties
Crank your flat top or skillet to medium-high heat. Place a beef ball down, sprinkle with salt, cover with a parchment square, and smash with a grill press until thin. Cook 2-3 minutes until craggy and deep golden brown, flip, add cheese, and cook another 1-2 minutes.
Whisk up the sauce
Mix mayo, ketchup, horseradish, Worcestershire, mustard, garlic, smoked paprika, and hot sauce. Season with salt to taste.
Assemble the burgers
Toast hamburger buns (butter them and bake at 400°F for 5 minutes). Build: bottom bun → sauce → caramelized onions → cheesy patty → tomato → pickles → lettuce → more sauce → top bun.
Summer grilling at its very finest. Caramelized onion burger FTW.
Expert Tips
- Low and slow for the onions y’all. If they’re burning, your heat is too high.
- Don’t skip the parchment paper square when smashing, it keeps the patties from sticking to the press.
- Chill the patties before smashing, it keeps them from falling apart.
- Don’t overmix the burger mixture or the burgers will be tough.
- Don’t put the salt in the meat mixture, wait to salt them as you are cooking (see FAQs for why).
- Usually I’m an American cheese hater buuuut it’s a classic flavor on a smash burger. I like to get mine freshly sliced from the deli counter.
- Lean ground beef is great, but don’t go too lean. I wouldn’t go leaner than 90/10, my preference is 80/20 grass-fed beef.
FAQs
My go-to is 80/20 ground chuck.
Yes! Caramelized onions keep in the fridge for 3-4 days. Rewarm before using.
You can make both the caramelized onions and burger patties in a cast iron skillet, stovetop griddle or cover the grill grates of a traditional grill with a grill mat.
When you mix salt into raw ground beef, the salt immediately starts dissolving proteins (specifically myosin). That makes the meat sticky and tight, instead of staying tender and juicy. By salting the beef on the grill right before (or as) it cooks, you season only the outside where the flavor matters most, let the inside stay tender and juicy, and get that gorgeous crust, since the salt pulls out a little moisture and helps browning.
Use a large, flat spatula. Basically, you just need something flat that you can press down on quickly.
Use gluten-free buns and ensure you’re using a gluten-free Worcestershire sauce.
What should I serve with this caramelized onion burger?
I love crispy air fryer fries, sweet potato fries, potato chips or any of the following:
Need a great way to make friends? Juicy burgers obvi.
If you try and like this recipe please don’t forget to leave a comment and star rating down below! If you love more lifestyle, behind the scenes and ‘eating in real life’ type of content come find me over on Instagram, @itsaflavorfullife, I love connecting with you all there!
Print
Caramelized Onion Burger Recipe
- Prep Time: 15 minutes
- Cook Time: 30 minutes
- Total Time: 45 minutes
- Yield: 4 smash burgers 1x
- Category: Dinner
- Method: Grill
- Cuisine: American
Description
Juicy caramelized onion burgers with melty cheese, special sauce, and buttery brioche buns. Easy and BEYOND good. The ultimate homemade smash burger recipe!
Ingredients
Equipment you need:
- parchment paper
- grill press
- flat top grill, indoor grill pan, large heavy-bottomed skillet or grill mats for a traditional grill* see notes
Patties
- 1 lb ground beef (I use 80/20)
- 2 tablespoons butter
- 1 Tablespoon Worcestershire sauce
- 1 teaspoon smoked paprika
- kosher salt
Caramelized Onions
- 2 sweet onions, thinly sliced
- 1 tablespoon each avocado oil and butter
- 2 teaspoons brown sugar
- 1 tablespoon balsamic vinegar
- pinch of salt
Special Sauce
- 1/2 cup mayo
- 2 tablespoons ketchup
- 1 teaspoon prepared horseradish
- 1 teaspoon Worcestershire sauce
- 1 teaspoon yellow mustard
- 1 clove garlic, grated or 1 teaspoon garlic paste
- 1/2 teaspoon smoked paprika
- dashes of hot sauce or sriracha
- pinch of salt, to taste
Assembly
- 4 brioche buns, toasted
- 4 slices American cheese
- Toppings: thinly sliced tomatoes, shredded lettuce, pickles, special sauce
Instructions
- Patties part one: Melt 2 tablespoons butter in a small bowl and stir in 1 tablespoon Worcestershire sauce and 1 teaspoon smoked paprika. Pour the butter mixture over the ground beef and use your hands to mix until just combined, don’t overmix it. Shape the mixture into four balls, put them on a plate and pop it in the fridge to chill while you prep the other components.
- Onions: Preheat flat top grill or large sauté pan over medium low heat. Melt 1 tablespoon butter and 1 tablespoon oil on the grill or in the pan. Add the sliced onions, tossing to get them evenly coated in fat. Cook over medium low, stirring occasionally for ten minutes until softened and starting to develop some color.
- Sprinkle on 2 teaspoons brown sugar, 1 tablespoon balsamic vinegar and a pinch of salt over the onions, tossing to combine. Continue cooking for 10-15 minutes, stirring every minute or so. Be careful to watch the heat, it’s best to go low and slow so the onions don’t burn. When the onions are deeply golden brown, caramelized and jammy, remove to a bowl.
- Patties part two: Increase grill heat to medium-high. Plop each ball onto the flat top and sprinkle with kosher salt. Place a small square of parchment paper on the patty and use a cast-iron grill press to smash the patty in one quick, aggressive motion. Really smash that bad boy, you’re going for a super thin patty. Repeat with the remaining patties. Cook for 2-3 minutes, until the burgers have craggly, browned edges. Flip and top with a slice of cheese, cooking for another 1-2 minutes. Remove to a plate, you’re ready for assembly!
- Assembly: Whisk together all of the ingredients for the special sauce. Taste and season with a pinch of salt or dash of sriracha, per your taste. Toast up the brioche buns (I like to butter them and bake at 400 degrees for 5 minutes). Layer -> bottom bun, huge spoonful of sauce, caramelized onions, beef patty, tomato, pickles, lettuce, huge spoonful of sauce, top bun.
WOWWWWW. Invite me over, I want one.
Notes
Cooking thoughts: I make the caramelized onions and smashburgers on the the flat top insert that goes in my grill. If you don’t have a flat top you have a few options: 1) you can make both the onions and burgers in a large pan on the stovetop 2) you could use an indoor grill pan or griddle or 3) you could use these nifty grill mats on a traditional grill. I used these with our old grill, they are awesome!
If you don’t have a grill press, use a large, flat metal spatula.
Refer to above blog post for step-by-step photos, expert tips and answers to frequently asked questions.
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Nutrition
- Serving Size: 1 smash burger
- Calories: 638
- Sugar: 10.5 g
- Sodium: 658.5 mg
- Fat: 42 g
- Carbohydrates: 29.7 g
- Fiber: 1.9 g
- Protein: 34.7 g
- Cholesterol: 115.7 mg
These were amazing!! Even my kids loved them!! And so easy to make!
We made this tonight. It was so flavorful! We cooked the burgers in our pizza oven. My husband said the burgers were restaurant quality. We will definitely be making this again. Served it with corn on the cob and homemade garlic potato wedges.
Yummmm, that meal sounds DELISH! So glad you loved it Laura, thanks for sharing!
I made it tonight! So good and delicious! served it with baked potatoes wedges!
I just need cook them outside next time 😂