Mushroom Swiss Burgers

From grocery.coop

Elevate your cheeseburger with an infusion of minced mushrooms and a hint of Worcestershire sauce.

8 oz button mushrooms
1/2 teaspoon olive oil
1 pound grass-fed ground beef
1 large egg
1 teaspoon Worcestershire sauce
1/2 teaspoon salt
1/2 teaspoon black pepper
4 slices Swiss cheese
4 hamburger buns

1. Place half of the mushrooms in a food processor and pulse several times to mince. Place a large skillet over medium-high heat and add the olive oil, then scrape the mushrooms into the hot pan. Add the remaining mushrooms to the food processor and mince, then add to the pan. Stir, scraping the bottom of the pan, until the mushrooms are sizzling and give up their liquids. Add the Worcestershire sauce, salt and pepper and reduce the heat to medium. Stir until the pan is dry, about 5 minutes. Transfer to a large bowl and let cool.
2. Add the ground beef to the mushroom mixture and stir with your hands to combine. Divide the mixture into 4 equal portions and gently shape into patties. Refrigerate until time to cook.
3. Grill or pan-fry the patties for about 3 minutes per side. When the burgers are done, top each with a slice of Swiss cheese and let sit in the hot pan for a few seconds to melt the cheese, then serve on toasted buns.