Use Your Grill
Heat grill to medium heat. Grill burgers 8 min. or until cooked through (160ºF), turning after 4 min. Toss onions and mushrooms with oil in foil pan; grill (in pan) along with the burgers.
Use Your Microwave
To prepare in just minutes, cook burgers following the microwave directions on package.
Substitute arugula leaves for the lettuce.