1. Cut bread into 1/2-inch slices and toast it lightly, either in a toaster or on the grill, taking care it doesn't burn.
2. Rub the crushed garlic clove all over the bread's surface. If the bread is properly toasted, it will pick up juice and particles from the garlic.
3. Slice the stem top off of the tomato and vigorously rub the cut side against the bread. The bread will absorb juice and pulp from the tomato, becoming soggy.
4. Drizzle with olive oil and sprinkle liberally with salt and pepper. Serve immediately.