Baby Bella Mushroom and Caramelized Onion Sliders

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Baby bellas are often positioned as a stand-in for beef burgers, especially in vegetarian cooking. That framing isn’t wrong, both the texture and depth of flavor hold their own, but it undersells what they do well on their own. Cooked properly, they’re substantial enough to satisfy without trying to imitate anything else.

Add sweet onions cooked down until soft, sharp cheddar, a restrained hit of sriracha, and baby bellas finished with balsamic, and the filling lands somewhere between earthy and rich, with enough heft to sit comfortably inside a soft slider bun.

Cleaning the mushrooms:
Mushrooms are rarely as clean as they look unless your store carries pre-washed ones. Rinse them briefly under cold running water and use a small vegetable brush to remove any grit from the surface—an old toothbrush works just as well. Baby bellas usually don’t have the tough stems you find on full-size portobellos, but if any feel woody, it’s best to remove them and use only the caps.

Tip:
Don’t throw those stems away. They’re useful for building a vegetable stock and work especially well in mushroom-based soups.

Baby Bella Mushroom and Caramelized Onion Sliders

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5 from 1 review

Author: Sukanya Ghosh
Total Time: 60 minutes
Yield: Serves 2
Diet: Vegetarian

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Description

Sweet caramelized onions and melted cheddar cheese top savory portabella mushrooms in these delightful vegetarian sliders. A dash of sriracha adds a kick!

Ingredients

Units Scale

1 box (approximately 10-12 mushrooms) Baby portabella mushrooms
2 tbsp or more Balsamic vinegar (aged)
2 cups (473 ml) Red onion (cut into rings)
2 Sharp cheddar cheese slices
2 Slider buns (or any other buns)
few Boston lettuce, rocket leaves and frissee or any other greens Greens
Salt, sugar and pepper
a dash of Sriracha sauce
2 tbsp (30 ml) Olive oil

Instructions

Wash the baby portabella mushrooms under cold running water and clean them thoroughly. Pat them dry and thinly slice them.
Caramelizing the onions
Heat some olive oil in a pan.
Cut the onions into rings and add them to the pan. Let them sweat for about 10 minutes over medium heat.
Sprinkle salt and sugar over the onions to help with caramelization. Stir occasionally. If they dry out, sprinkle with a little water.
After 20 minutes, lower the heat and let the onions stick to the bottom slightly before stirring. Continue until nicely caramelized (about 30 minutes total).
Making the mushroom melt
In another pan, heat some olive oil. Once simmering, add the sliced mushrooms.
Let the mushrooms sweat for a few minutes.
Once the mushrooms start changing color, add black pepper powder. Take care not to burn them.
Deglaze the pan with balsamic vinegar and let the mushrooms soak up the flavor for another 5 minutes.
Check for seasoning; add salt if needed. The mushrooms will be fully cooked in 10 minutes.
Meanwhile, warm the buns on a griddle.
While the mushrooms are still warm, separate them into servings and top with cheddar cheese slices (extra sharp cheddar is recommended).
Let the cheese melt on top of the mushrooms.
Arrange the buns on a serving plate and add greens.
Assemble the sandwich: base bun, greens, mushroom melt, caramelized onions, and a dash of Sriracha sauce.
Serve immediately.

Notes

For deeper caramelization, add a pinch of brown sugar to the onions.
Substitute Gruyere or Monterey Jack cheese for the cheddar.
Store leftover caramelized onions in an airtight container in the refrigerator for up to 5 days.

Prep Time: 20 minutes
Cook Time: 40 minutes
Category: Sandwich
Method: Sautéing
Cuisine: American