How do I prevent the onions from burning while I caramelize them?

I cook sliced yellow onions over medium heat in a large skillet with a bit of oil and a pinch of salt, stirring often. If they start to stick or brown too fast, I lower the heat and add a splash of water or a touch of butter. Patience is key — low and slow yields deep, golden flavor without burning.

What grind and fat ratio of beef should I use for the crispiest edges?

I use 85/15 ground beef for a good balance of juiciness and fat needed to form thin, crispy-edged patties when smashed on a very hot cast-iron skillet. The higher fat renders and helps create the Maillard crust I want.

How do I make the truffle aioli so it’s bright and not overly oily?

I whisk together mayonnaise, minced garlic, lemon juice, and a small amount of black truffle oil in a small bowl. The lemon juice brightens the mayo and cuts through richness; I add truffle oil sparingly and season with salt and pepper to taste so the aroma is balanced, not overpowering.

Can I skip the truffle oil or substitute it if I don’t have any?

Yes. I sometimes skip truffle oil and add a teaspoon of mushroom paste or finely minced sautéed mushrooms for umami, or use a few drops of truffle-infused salt instead. These swaps give a similar earthy note without the intense perfume of straight truffle oil.

How long does it take to caramelize onions properly?

I plan on 25–40 minutes to get deeply golden-brown onions, depending on pan size and heat. Stir regularly and adjust heat so they slowly soften and darken; rushing at high heat risks bitter, burnt edges instead of sweet complexity.

What’s the best way to toast buns for this sandwich?

I butter the cut sides lightly and toast them in the same skillet over medium heat until golden. Using the pan after cooking the patties adds flavor from the fond and keeps the buns crisp where they meet the patties.

Should I season the beef before smashing, and when do I add salt and pepper?

I form loosely packed beef balls and place them on the hot skillet, then immediately season the top with salt and ground black pepper before smashing. Seasoning before contact helps build the crust; I add a final pinch after flipping if needed.

Do I need to rest the patties after cooking?

For thin smash patties I don’t rest them long because they cool quickly. I typically add the cheese, let it melt briefly, then assemble right away so the bun and aioli capture the juices while the patty is still hot.

Can I add mushrooms to the recipe, and how should I prepare them?

I often add sliced mushrooms as an optional mix-in. I sauté them first in butter or oil until golden and set them aside with the onions. If you want an earthy boost instead of truffle, mixing mushrooms into the aioli or layering them on the patty works well.

What cheese works best if I don’t have Swiss or Gruyère?

I recommend white cheddar or provolone as smart swaps; they melt nicely and complement the savory components. Choose a slice that melts quickly so it blankets the patty without overpowering the truffle notes.

My Truffle-Swiss Caramelized Onion Smash Burger with Garlic Aioli Swirl

Description

Gourmet truffle smash burger with caramelized onions, Swiss cheese, and homemade garlic aioli. Crafted for discerning home chefs seeking restaurant-quality results with weeknight-friendly techniques.

Ingredients

Scale

1 lb ground beef (85/15)

1 tsp truffle oil

1/2 tsp salt

1/4 tsp ground black pepper

1 large yellow onion, thinly sliced

1–2 tablespoons oil

1 tbsp butter

4 slices Swiss cheese

4 hamburger buns

1/2 cup mayonnaise

2 cloves garlic, minced

1 tsp lemon juice

Additional salt and pepper to taste

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Instructions

1. Heat 1-2 tablespoons oil in large skillet over medium heat. Add sliced onions with pinch of salt and cook, stirring often, for 30-40 minutes until deeply golden brown.

2. Whisk together mayonnaise, minced garlic, lemon juice, and truffle oil in small bowl. Season with salt and pepper to taste. Set aside.

3. Portion ground beef into loose 2.5-3 oz balls. Heat cast-iron skillet over medium-high heat until very hot.

4. Smash each beef ball in hot skillet for 2-3 minutes to build crisp edges. Season immediately with salt and pepper. Flip, add cheese slice, cook 1-2 minutes more to melt.

5. Lightly butter cut sides of buns and toast in same skillet until golden.

6. Assemble burgers: spread aioli on bottom bun, add patties, pile caramelized onions, top with remaining bun half and serve immediately.

Notes

Use 85/15 ground beef for optimal juiciness and crispy edges when smashed.

Caramelized onions can be made ahead and reheated gently before serving.

Truffle aioli keeps in refrigerator up to 5 days – make ahead for quick assembly.

Swiss or Gruyère cheese both work perfectly – choose your preference.

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Prep Time: 15
Cook Time: 45
Category: gourmet-appetizers
Method: pan-seared
Cuisine: American-gourmet

Nutrition

Serving Size: 1
Calories: 650
Sugar: 8g
Sodium: 890mg
Fat: 42g
Saturated Fat: 18g
Unsaturated Fat: 20g
Trans Fat: 0g
Carbohydrates: 32g
Fiber: 3g
Protein: 35g
Cholesterol: 95mg