Skillet Turkey Mushroom Burgers with Caramelized Onions

Steps

1. Prep first: chop the mushrooms, mince the garlic, slice the onion, slice the tomato and separate, rinse and dry the romaine leaves.
2. Heat half of the olive oil in a large skillet over medium-low heat. Add the onion and cook, stirring often, 15 to 20 minutes until soft and golden. Move the onion to a bowl.
3. Raise the heat to medium-high. Add the mushrooms to the same skillet and cook 6 to 8 minutes until their liquid evaporates and they brown. Add the garlic for the last 30 seconds, then spread the mixture on a plate to cool for 5 minutes. Wipe out the skillet.
4. In a large bowl, mix the cooled mushroom mixture with the egg, breadcrumbs, Worcestershire sauce, thyme, salt and black pepper. Add the turkey and mix gently with your hands just until combined.
5. Shape the turkey mixture into 4 patties about 3/4 inch thick, pressing a slight dimple in the center of each.
6. Heat the remaining half of the olive oil in the skillet over medium heat. Cook the patties 5 to 6 minutes per side until well browned and 165°F (74°C) in the center.
7. Stack two or three romaine leaves per burger. Spread each patty with the mustard, set it on the lettuce, and top with the tomato and the caramelized onion. Fold the leaves around and serve.