Add the vinegar to a small saucepan and bring it to a boil.

Reduce the heat to low and simmer until reduced by half.

Remove the saucepan from the heat and allow to cool.

Preheat the oven to 400 degrees Fahrenheit and set a baking sheet to the side.

Add the minced garlic to the butter and mix well.

Cut the loaf of bread in half, lengthwise.

Butter the cut sides with the garlic butter.

Place the bread on a baking sheet with the cut side up.

Place the mozzarella cheese slices on top of the bread.

Bake for about 12 minutes, until cheese is melted and edges are starting to brown.

Top with the sliced tomatoes.

Top tomatoes with chopped basil and salt and pepper to taste.

Drizzle with balsamic reduction.

Cut into slices and serve.