Portobello Mushroom Burger

Heat a large skillet over medium or medium low heat. When hot, add butter. Once butter has melted, add sliced onion and cook for about 15–20 minutes, or until golden brown and caramelized.

In the last minute or two, deglaze pan with a couple splashes of dry white wine. Cook until wine has absorbed. Set aside.

Preheat broiler (ours is at 500ºF). Gently wash and dry mushroom caps. Place them ribbed side up on a rimmed baking sheet.

Whisk together olive oil and balsamic vinegar in a small bowl. Brush half of the oil-vinegar mixture on the ribbed sides of the mushrooms. Broil for 5 minutes. Flip mushrooms and brush on remaining oil-vinegar.
Broil for another 5 minutes. Remove from the oven and sprinkle with a little salt.

To assemble burgers, spread softened goat cheese on the bottom bun. Top with spinach, then portobello mushroom. Top that with some caramelized onions and 1 tablespoon pesto. Top with burger bun.

Notes:
1. Some of the oil and vinegar will roll off the mushrooms and may start to smoke on the pan. Don’t worry, it’s totally normal!
2. After mushrooms were cooked, Trevor cut the mushrooms to fit the size of bun we have on hand. This isn’t necessary, but makes for a really pretty presentation!
3. Gluten-free? Make sure to use a gluten-free bun!