Bring hearty steakhouse flavor to your backyard barbecue by topping burgers with sautéed mushrooms and onion and Swiss cheese.
Heat oil in large skillet on medium-high heat. Add mushrooms and onion; cook and stir 4 to 5 minutes or until tender. Set aside.
Mix ground beef and Seasoning Mix until well blended. Shape into 4 patties.
Grill over medium heat 4 to 6 minutes per side or until burgers are cooked through (internal temperature of 160ºF). Add cheese slices to burgers 1 minute before cooking is completed.
Serve burgers on rolls topped with mushroom and onion mixture, lettuce and desired condiments.