Mushroom Swiss Burger Onions (Printable)
Savor a juicy beef burger topped with sautéed mushrooms, melted Swiss cheese, and caramelized onions on a toasted bun.
# What You'll Need:
→ Caramelized Onions
01 - 2 large yellow onions, thinly sliced
02 - 2 tbsp unsalted butter
03 - 1 tbsp olive oil
04 - 1/2 tsp salt
05 - 1/2 tsp sugar
06 - 1 tbsp balsamic vinegar (optional)
→ Mushrooms
07 - 9 oz cremini or button mushrooms, sliced
08 - 1 tbsp unsalted butter
09 - 1 tbsp olive oil
10 - 1 clove garlic, minced
11 - Salt and pepper, to taste
→ Burgers
12 - 1.3 lbs ground beef (80/20 blend recommended)
13 - 1 tsp salt
14 - 1/2 tsp black pepper
15 - 4 slices Swiss cheese
16 - 4 brioche or hamburger buns
17 - 1 tbsp unsalted butter, softened (for toasting buns)
→ Optional Toppings
18 - Fresh lettuce leaves
19 - Sliced tomatoes
20 - Dijon mustard or mayonnaise
# How To Make:
01 - Melt butter with olive oil in a large skillet over medium heat. Add sliced onions, salt, and sugar. Cook, stirring frequently, until onions turn deeply golden and soft, about 20 minutes. Stir in balsamic vinegar during the last 2 minutes if used. Remove from heat and set aside.
02 - In a medium skillet over medium-high heat, melt butter with olive oil. Add mushrooms and cook until browned and tender, approximately 7 minutes. Add minced garlic, season with salt and pepper, and cook for 1 additional minute. Remove from heat and set aside.
03 - Shape ground beef into 4 equal patties, each approximately 3/4 inch thick. Season both sides with salt and black pepper.
04 - Preheat grill or skillet over medium-high heat. Cook patties for 3 to 4 minutes per side until medium doneness or preferred level. During the last minute of cooking, place a slice of Swiss cheese on each patty and cover to melt.
05 - Spread softened butter on the cut sides of the buns. Toast on a skillet or grill, cut side down, until golden brown.
06 - Place lettuce and tomato slices on the bottom bun. Add the cheese-topped patty, then layer sautéed mushrooms and caramelized onions. Spread Dijon mustard or mayonnaise on the top bun if desired. Close and serve immediately.
# Expert Tips:
01 -
- The caramelized onions are so naturally sweet you'll find yourself eating them straight from the pan with a spoon.
- Everything can be prepped ahead, so dinner comes together in minutes when you're actually hungry.
- It tastes like you spent hours cooking when you really only spent about 45 minutes, most of which is just letting things do their thing.
02 -
- Caramelization takes actual time—about 20 minutes minimum—and there's no shortcut that tastes authentic; medium heat is slower but gives you that deep flavor, not burnt bits.
- Don't press your burgers while they cook; it squeezes out all the juices and defeats the purpose of using a fattier beef blend in the first place.
- Toast your buns or they'll absorb all the moisture from the toppings and fall apart the moment you take a bite.
03 -
- Make all your components ahead of time; the onions and mushrooms are actually better after they've cooled and can be reheated quickly, leaving you free to focus on cooking the burgers perfectly at the last minute.
- If your buns aren't fresh, sprinkle a tiny bit of water on them before toasting—it refreshes them and keeps them from drying out as they warm.