Burgers with Onions & Mushrooms

Adapted from recipes by My Nourished Home and The Kitchn, shared by My Saratoga Kitchen Table

Serves: 8

Ingredients

*Ingredients currently available at the farmers’ market

For the Onions and Mushrooms:

• 2 to 3 Tablespoons olive oil
• 3 Tablespoons butter
• 2 large sweet onions*
• 16 ounces mushrooms* (shitake* and/or oyster*)

For the burgers:

• 2 pounds ground beef*
• 1/2 small onion*, finely chopped
• 2 teaspoons Worcestershire sauce
• 2 teaspoons tamari or soy sauce
• 1 teaspoon garlic powder
• Freshly ground black pepper
• 6 hamburger buns, split

Instructions

For the onions the mushrooms:

1. In a large saute pan, heat the oil and butter on medium-low. Peel and slice the onions into long, thin slices. Place the onions in the pan, add salt and pepper to taste, and carefully toss to coat all the onions in the oil and butter. Allow to caramelize, stirring occasionally for 20 to 30 minutes. They’ll turn a warm brown color.
2. Add the mushrooms to the onions, carefully toss to coat them with oil. Continue to cook on medium-low. The mushrooms will become soft and browned.

For the burgers:

1. Heat the grill. Heat an outdoor grill to high heat (about 450°F). On a charcoal grill, arrange the coals to create high heat and a low heat cooking zone (direct and indirect grilling). Meanwhile, prepare the burger patties.
2. Season the beef. Place the ground beef on a baking sheet and gently pat it into a log. Use your thumb to make a deep trough in the center. Sprinkle the onions evenly into the trough. Whisk the Worcestershire, tamari or soy sauce, and garlic powder together in a small bowl. Sprinkle this over the onions. Finish with a few grinds of fresh black pepper over everything.
3. Shape the patties. Pinch the ground beef closed around the onions. Divide the meat into 8 equal portions using a chef knife, a bench scraper, or your fingers. Use your hands to gently flatten each portion into a patty about 1-inch thick. Try not to compact or overwork the meat. Let the burgers sit at room temperature until the grill is ready, about 20 minutes.
4. Grill the burgers. Place the patties on the grill in a single layer. Cook until grill marks appear about 2 minutes. Flip and cook until grill marks appear on the second side, about 2 minutes more. If using a charcoal grill, move the patties to a lower-heat (indirect) area of the grill. If using a gas grill, reduce the heat to medium. Grill 2 to 3 minutes more for medium-rare burgers, 3 to 4 minutes more for medium, or 5 to 6 minutes more for well-done burgers. 
5. Assemble the burgers. Place a patty on each toasted bun and serve with toppings.