- 1 medium onion
- 2 tablespoons butter
- 1 cup mushroom, sliced
- sea salt
- 1 teaspoon balsamic vinegar
- 4 slices swiss cheese
- 8 slices sourdough bread
Directions See How It's Made
- Slice the onion and saute in butter over medium heat until soft and golden brown, about 7-10 minutes, stirring occasionally.
- Stir in mushrooms, cook at stir 2-3 minutes more; remove from heat.
- Sprinkle onions and mushroom with sea salt and balsamic vinegar.
- Place slices of cheese on 4 pieces bread, top each with onion-mushroom mixture and another slice of bread.
- Cook on a griddle or skillet over medium heat until cheese is melted, 2-3 minutes per side.