¼ cup extra virgin olive oil
6 cloves garlic, minced
1 teaspoon red pepper flakes
1 tablespoon balsamic vinegar
pinch of sea salt
8 large portabello mushrooms, gills scraped out with a spoon
½ sweet onion, cut crosswise into 4 thick slices
1 large firm tomato, cut crosswise into 4 thick slices
4 ounces fresh mozzarella cheese, sliced into 8 slices
4 mini whole grain ciabiatta buns (or other whole grain bun), halved
1/4 cup faux aioli