1. Mix beef with egg, onion, bread crumbs, garlic, 1/2 teaspoon salt, and 1/4 teaspoon pepper. Form into 4 equal patties about 1/2 inch thick.
2. Place an 11- to 12-inch nonstick frying pan over medium-high heat.
3. When pan is hot, add beef patties and brown on each side, cooking until a thermometer inserted in center of thickest part reads 160° (no pink in the center), 7 to 8 minutes total.
4. With a spatula, transfer beef patties to buns. Add salt and pepper to taste.