2 pounds Ground Beef
3 teaspoons Worcestershire sauce
1 and 1/2 teaspoons Kosher salt, divided
1 teaspoon freshly ground pepper, divided
3 tablespoons olive oil
16 ounces sliced baby bella mushrooms
1 medium onion, thinly sliced
8 slices Swiss cheese
8 2-ounce whole-grain hamburger buns, toasted
1 cup barbecue sauce, divided
4 cups arugula
Combine Ground Beef, Worcestershire sauce, 3/4 teaspoon salt and 1/2 teaspoon black pepper in a large bowl, gently mixing until fully incorporated. Be careful not to over mix. Shape Ground Beef into 8 patties.
Heat olive oil over medium heat in a medium skillet. Add mushrooms and onions. Cook until tender, about 10 minutes, stirring frequently. Add 3/4 teaspoon salt and 1/2 teaspoon freshly ground black pepper. Keep warm.
Light charcoal grill. The fire should be quite hot; you should barely be able to hold your hand 3 or 4 inches over the grates. After the coals are gray, spray grates with cooking spray or brush with oil to help keep burgers from sticking.
Place patties on grill and cook about 4 minutes per side for rare, and another minute per side for each increasing stage of doneness. Top each burger with Swiss cheese the last 2 minutes of cooking time or until melted.
Place burgers on bottoms of buns. Evenly top burgers with sautéed mushrooms and onions. Drizzle 2 tablespoons of barbecue sauce on each burger. Top each burger with 1/4 cup arugula.