Stuffed Pork Burgers

1/2 cup chopped fresh mushrooms
1/4 cup sliced green onions
1/4 teaspoon garlic powder
1 tablespoon butter
2 tablespoons Worcestershire sauce
1 teaspoon ground mustard
1/2 teaspoon salt
1/2 teaspoon pepper
1-1/2 pounds ground pork
4 kaiser rolls, split
4 lettuce leaves
4 slices red onion
8 thin slices tomato
Prepared mustard

In a small skillet, saute the mushrooms, onions and garlic powder in butter until vegetables are tender. Remove from the heat. In a large bowl, combine the Worcestershire sauce, mustard, salt and pepper. Crumble pork over mixture and mix well. Shape into eight patties. Spoon mushroom mixture into the center of four patties to within 1/2-in. of edges. Top with remaining patties; pinch edges to seal. Grill, uncovered, over medium heat for 5-7 minutes on each side or until a meat thermometer reads 160° and meat juices run clear. Serve on rolls with the lettuce, onion, tomato and mustard. Yield: 4 servings.