In a bowl add soup mix to ground beef and mix together with your clean hands. Form hamburger patties about 1/2 inch thick. Grill for about 5 minutes. While burgers are grilling, stir fry mushrooms in olive oil and add 1/2 teaspoon salt. Slice rolls in half.
Turn burgers and cook for another 4 to 5 minutes. Place cheese slices on top of burgers to melt. Brush French rolls with olive oil and grill for 1 to 2 minutes. Remove burgers and rolls from grill.
Place burgers on French rolls and top with mushrooms. Add mustard, ketchup, or mayonnaise and your favorite toppings.