Lamb Burgers With Quick Skillet Ketchup

• 1/2 cup Champagne vinegar
• 1/2 cup water
• 1/4 cup granulated sugar, divided
• 1 tablespoon plus 1/2 tsp. kosher salt, divided
• 3 ounces shiitake mushrooms, thinly sliced
• 2 tablespoons canola oil
• 20 ounces ground lamb
• 1 1/2 teaspoons black pepper, divided
• 1 pint cherry tomatoes
• 3 garlic cloves, minced
• 1 cup white vinegar
• 4 hamburger buns
• 4 ounces blue cheese, crumbled (about 1 cup)
• 1 cup packed watercress

1. Preheat broiler with oven rack 6 to 8 inches from heat. Combine Champagne vinegar, water, 1 tablespoon of the sugar, and 1 teaspoon of the salt in a microwavable bowl; microwave on HIGH 1 minute and 30 seconds. Add mushrooms; chill, uncovered, 10 minutes.
2. Heat oil in a large cast-iron skillet over medium-high. Shape lamb into 4 (1/4-inch-thick) patties. Sprinkle evenly 1 teaspoon each of the salt and pepper. Cook patties until browned and done, about 4 minutes per side. Transfer to a plate lined with paper towels.
3. Add tomatoes and garlic to skillet; cook, stirring often, until garlic begins to brown, about 2 minutes. Add white vinegar and remaining 3 tablespoons sugar, 1 1/2 teaspoons salt, and 1/2 teaspoon pepper; cook, stirring occasionally, until tomatoes begin to burst, about 10 minutes. Using a large spoon, press tomatoes, and cook, pressing occasionally, until almost all of the liquid is evaporated, about 10 minutes. Transfer tomato mixture to a bowl; cool 5 minutes.
4. Place 1 patty on each bottom hamburger bun. Top each patty with 1/4 cup cheese. Broil in preheated oven 2 minutes. Top patties evenly with tomato mixture, mushrooms, and watercress. Cover with top buns.

vinegar, water, granulated sugar, kosher salt, shiitake mushrooms, canola oil, ground lamb, black pepper, tomatoes, garlic, white vinegar, buns, blue cheese, watercress

Taken from www.myrecipes.com/recipe/ground-lamb-burgers (may not work)