Italian Burgers with Cucumber Mushroom Salsa
1/4 small sweet onion, thinly sliced
1/4 cucumber, thinly sliced
1 large fresh mushroom, thinly sliced
1/4 cup plus 3 tablespoons prepared zesty Italian salad dressing, divided
1 1/2 pounds ground sirloin
Vegetable oil, for brushing the grill rack
6 slices mozzarella cheese
6 soft Kaiser rolls
6 romaine lettuce leaves, torn to fit bun
1 tomato, sliced
Combine onion, cucumber and mushroom in a medium storage container with tight fitting lid. Add 1/4 cup salad dressing, cover tightly and shake. Refrigerate for one to four hours.
Combine remaining 3 tablespoons salad dressing and ground sirloin in a large mixing bowl, handling the meat as little as possible to avoid compacting it; mix well. Divide the mixture into 6 equal portions, forming into patties to fit bun size. Loosely cover with plastic wrap and refrigerate.
Prepare a medium fire in a charcoal grill with a cover, or preheat a gas grill to medium. Brush the grill with vegetable oil. Place patties on grill, cover and grill for 5 minutes. Turn patties, and continue grilling for 4 minutes. Place cheese slices on the patties during the last 3 minutes of grilling. Place the buns, cut side down, on the outer edges of the rack to toast lightly during the last 2 minutes of grilling.
To assemble each burger, line bun bottom with lettuce. Drain salsa, arrange on lettuce; then top with burger, tomato slice and bun top. Serve immediately.