This is a wonderful sandwich that tastes like a bowl of classic French Onion Soup!
1 T oil
1 Vidalia onion
2 cloves garlic, minced
1 t sea or kosher salt
1 t basil leaves, minced
2 ounces white wine
4 slices crusty bread
2 T butter
6 slices mozzarella cheese
Peel and halve the onion. Slice as thin as possible, less than 1/4". Smash garlic cloves, peel, and mince. Heat a heavy skillet over medium heat with butter and oil. When butter has melted, add the onion and garlic. Season with salt and pepper. Add minced basil. Stir to blend. Sauté mixture until onions have softened completely and most of their water has cooked away. Add wine and continue to sauté until most of the wine has cooked off and onions have begun to caramelize slightly.
While onions and garlic are cooking, set oven to broil. Lightly spread butter on bread slices. Arrange them on a baking sheet. Set under broiler until golden brown, about 2 minutes. Remove from oven and turn all slices of bread over. Arrange 6 slices on two of the bread slices.
Optional*** Spread the slices of bread with Dijon mustard or any gourmet mustard you prefer - as much as you like.
Use tongs to divide the onion and garlic mixture between two slices. Broil until cheese is melted and onions are well caramelized. This will only take a couple of minutes. Remove baking sheet from oven. Use tongs to lift and turn over the slices covered with cheese onto the slices covered with onions. Cut each sandwich in half, and serve while still hot.