Smoky Bacon Burgers

Ingredients

• 1 pound very lean grnd beef
• 1 egg
• 1 c. finely minced onion
• 3/4 teaspoon salt
• 1/4 teaspoon black pepper
• 1/2-1 teaspoon liquid smoke flavoring
• 4 slices bacon
• 4 lettuce leaves
• 4 tomato slices
• 4 toasted hamburger buns