Balsamic Portobello Mushroom Burger with Avocado and Spicy Mayo

These portobello mushroom burgers are so hearty and satisfying, you won’t miss the beef. The mushrooms are seared until golden, then finished with a splash of balsamic vinegar that adds a tangy sweetness. Piled onto warm buns with caramelized onions, a kick of spicy mayo and creamy mashed avocado, every bite is packed with flavor and texture.

Perfect for summer cookouts or a quick weeknight dinner, this recipe comes together in about 30 minutes. Serve with a simple side salad to round out the meal. It’s a delicious way to enjoy a plant-based burger that’s anything but boring.

Log in to save recipes and build weekly shopping lists.

Ingredients

4 portobello mushroom capsView ingredient guideLike ingredientDislike ingredient

2 tablespoons balsamic vinegarView ingredient guideLike ingredientDislike ingredient

2 tablespoons olive oilView ingredient guideLike ingredientDislike ingredient

Salt and pepper to tasteView ingredient guideLike ingredientDislike ingredient

1 large onion, thinly slicedView ingredient guideLike ingredientDislike ingredient

1 tablespoon butter or oil for caramelizingView ingredient guideLike ingredientDislike ingredient

4 burger buns, split and toastedView ingredient guideLike ingredientDislike ingredient

1 ripe avocadoView ingredient guideLike ingredientDislike ingredient

1/4 cup mayonnaiseView ingredient guideLike ingredientDislike ingredient

1 teaspoon sriracha or hot sauce (adjust to taste)View ingredient guideLike ingredientDislike ingredient

2 cups mixed salad greensView ingredient guideLike ingredientDislike ingredient

1 tablespoon lemon juiceView ingredient guideLike ingredientDislike ingredient

Instructions

1. Heat 1 tablespoon olive oil in a skillet over medium heat. Add sliced onions and cook, stirring occasionally, until soft and caramelized, about 10-12 minutes. Season with salt and pepper. Set aside.
2. While onions cook, prepare the spicy mayo: in a small bowl, mix mayonnaise with sriracha (or hot sauce) until well combined. Set aside.
3. Mash the avocado with a fork until smooth but still slightly chunky. Season with salt, pepper and lemon juice. Set aside.
4. Wipe portobello caps clean with a damp paper towel. Remove stems if desired. Brush both sides with remaining 1 tablespoon olive oil and season with salt and pepper.
5. Heat a grill pan or large skillet over medium-high heat. Cook portobello caps for 3-4 minutes per side, until tender and grill marks appear.
6. Reduce heat to low. Drizzle balsamic vinegar over the mushrooms and cook for 1 more minute, turning to coat. Remove from heat.
7. Toast burger buns on the grill or in a toaster until lightly golden.
8. Assemble burgers: spread spicy mayo on bottom bun, top with a portobello cap, caramelized onions, a dollop of mashed avocado and a handful of salad greens. Close with top bun. Serve immediately.

Recipe Tips

FAQ

Can I use a different type of mushroom?

Portobellos are ideal for their meaty texture and large size, but you can substitute with large cremini mushrooms if needed.

How do I prevent the mushrooms from becoming soggy?

Make sure to cook them over high heat to sear quickly and avoid overcrowding the pan. Pat them dry before cooking.

Can I make this recipe vegan?

Yes, use vegan mayonnaise and substitute butter with oil for caramelizing onions. The rest of the ingredients are plant-based.