Mushroom-Topped Burgers with Slow-Roasted Tomato Ketchup
Prepare Slow-Roasted Tomato Ketchup; set aside.
For cheese crisps, heat oven to 400F. Line a large baking sheet with parchment. Space eight 2-Tbsp. mounds of cheese at least 3 inches apart. Bake 10 minutes, until bubbly and lightly browned. Cool on baking sheet.
Meanwhile, in large skillet over medium-high heat cook mushrooms, thyme, and salt in hot oil for 5 minutes, until mushrooms are tender.
Build charcoal fire or preheat gas grill for direct cooking. In a large bowl gently mix ground chuck with garlic and additional salt and pepper, and form into six 3/4-inch patties. Press indentation into each patty. Place patties on grill over medium heat; cover and grill 10 to 12 minutes or until done (160 degrees F), turning once halfway through. Remove from grill. Line bun bottoms with lettuce and cheese crisps. Top with burgers. Spoon ketchup and mushrooms over burgers and top with bun tops.
Slow-Roasted Tomato Ketchup
Preheat oven to 275 degrees F. On a parchment paper-lined baking sheet; add onion to baking sheet. Sprinkle tomato halves with brown sugar and salt; drizzle tomatoes and onion with olive oil. Roast, uncovered, for 2 hours or until onions are browned and tomatoes are softened but still moist.
Transfer tomatoes and onions to a blender or food processor. Cover and blend or process until smooth. Transfer to a small bowl. Stir in hoisin. Let stand until ready to use. Cover and chill any remaining ketchup for up to 1 week.