Pulse half an onion in food processor. Make burger patties: Combine ground beef (80/20), onion, and Worcestershire sauce, and form into 1/4 lb. patties. Add salt and pepper to the outside — this should help form a crust in the air fryer. Add the patties to the air fryer for 14 to 15 minutes. Make gravy: Slice onions into half moons and cook down with oil until translucent. Slice whole mushrooms lengthwise and add to onions. Sauté until tender, then add in beef stock. Bring to a boil then reduce to simmer. Add in 1/4-1/2 can Campbell’s® Cream of Mushroom Soup (this also acts as the thic...