This is a great way to use up leftover roasted red peppers. When I and my two brothers and sister were kids, my parents often served it as an afternoon snack to ward off our hunger before dinner was ready.
Preheat the Oven to 375 degrees F. Arrange the bread slices on a baking sheet. Brush the bread with oil and bake until the bread is pale golden and crisp, about 15 minutes. (The crostini can be prepared up to this point 1 day ahead. Cool, then store airtight at room temperature. Return the crostini to a baking sheet before proceeding.)
Preheat the broiler. Arrange the bell pepper strips atop the crostini and sprinkle with the cheese. Broil until the cheese melts, about 2 minutes. Transfer the crostini to a platter and serve immediately.