Guacamole Burgers

Name: Guacamole Burgers
Ingredients: For the Guacamole; 2 ripe avocados from Mexico, peeled, pitted, and mashed; 1 small red, ripe tomato, diced; 1/2 cup cilantro leaves, chopped; 1/4 teaspoon salt; Juice of one lime; 1 jalapeno, stem and seeds removed, finely diced (optional); For the Burgers; 2 pounds ground sirloin, formed into four patties; 1 teaspoon steak seasoning; 4 hamburger buns; 4 ounces 1-oz slices cheddar cheese; Green leaf lettuce; 2 ripe, red tomatoes, sliced; 1 small onion, peeled and thinly sliced