Peel the onions and cut into fine strips. Grate the cheese.
Heat up a large skillet with 2 tablespoons butter over medium high heat. Add the onions and season with salt and pepper. Cover and cook, stirring once or twice for 3-5 minutes, until the onions are softened. Uncover, reduce the heat to medium-low, and cook for 20-25 minutes, stirring occasionally, until deep golden brown.
Deglaze the skillet with vinegar and cook until the liquid has evaporated, about 1 minute. Transfer the onions to a medium bowl and season to taste with salt and pepper.
Add the cheese to the onions and stir to combine.
Heat up a medium skillet with 1 tablespoon butter over medium high heat. Scoop the cheese onion mixture on 2 slices of bread and top with remaining slices of bread. Press down gently.
Grill the sandwiches for 3-4 minutes, until the bottoms turn golden brown. Add the remaining 1 tablespoon butter, flip the sandwiches, press down and grill until the cheese has fully melted and the bottoms turn golden brown as well.
Preparing In The Kitchen
Peel the onions and cut into fine strips. Grate the cheese.
Heat up a large skillet with 2 tablespoons butter over medium high heat. Add the onions and season with salt and pepper. Cover and cook, stirring once or twice for 3-5 minutes, until the onions are softened. Uncover, reduce the heat to medium-low, and cook for 20-25 minutes, stirring occasionally, until deep golden brown.
Deglaze the skillet with vinegar and cook until the liquid has evaporated, about 1 minute. Transfer the onions to a medium bowl and season to taste with salt and pepper.
Add the cheese to the onions and stir to combine.
Heat up a medium skillet with 1 tablespoon butter over medium high heat. Scoop the cheese onion mixture on 2 slices of bread and top with remaining slices of bread. Press down gently.
Grill the sandwiches for 3-4 minutes, until the bottoms turn golden brown. Add the remaining 1 tablespoon butter, flip the sandwiches, press down and grill until the cheese has fully melted and the bottoms turn golden brown as well.