2 cups green beans 1/4 cup olive oil 2 cloves garlic, roughly chopped pinches red pepper flakes (to taste—but be generous) pinches salt pinches freshly ground black pepper 2 to 3 tablespoons red wine vinegar 4 focaccia rolls, halved (or 8 slices of focaccia; if you've made a pan of focaccia, slice 4 big squares and then cut each in half so you have 8 thin squares of focaccia) 4 ounces fresh mozzarella, sliced very thinly