Cheddar Burgers With Balsamic Onions And Chipotle Ketchup

• Onions
• 1 lb red onion, cut crosswise into 1/3 to 1/2 inch rounds
• olive oil
• 3/4 teaspoon kosher salt
• 1/2 teaspoon fresh coarse ground black pepper
• 2 tablespoons balsamic vinegar
• Chipotle Ketchup
• 1 cup ketchup
• 1 1/2 teaspoons chopped chipotle chilies, from canned chipotle chilies in adobo
• 2 tablespoons adobo sauce, from can
• 2 teaspoons balsamic vinegar
• Burgers
• 2 1/4 lbs 80% lean ground beef (15%-20% fat)
• coarse kosher salt
• 6 slices sharp cheddar cheese (thick slices)
• 6 large English muffins or 6 large hamburger buns, split & grilled
• 6 slices tomatoes
• 2 cups fresh spinach leaves

1. Onions:
2. DO AHEAD; CAN BE MADE UP TO 3 DAYS AHEAD! Prepare grill to medium high heat. Arrange onion rounds on baking sheet. Brush with oil; sprinkle with 3/4 teaspoon coarse salt and pepper. Transfer onion rounds to grill rack; close cover. Cook until onions are tender, about 10 minutes. Transfer to a medium bowl. Toss with vinegar. Cover and chill.
3. Chipotle Ketchup:
4. DO AHEAD; CAN BE MADE UP TO 3 DAYS AHEAD!
5. Mix ketchup, chilies, adobo sauce, and 2 teaspoons vinegar in small bowl. Season with salt and more vinegar, if desired. Cover and chill.
6. Burgers:
7. Shape beef into 6 1/2 inch-thick patties. Sprinkle patties on both sides with coarse salt and pepper.
8. Prepare grill to medium high heat. Place burgers on grill. Close cover; cook burgers until bottoms start to darken and juices rise to surface, about 3 minutes. Turn burgers; cook to desired doneness, about 3 minutes longer for medium-rare. Top with onions and cheese. Close cover; cook until cheese melts.
9. Place grilled English muffin or bun bottoms on plates; spread with ketchup. Top with burgers, tomatoes, spinach, and grilled muffin tops. Serve, passing remaining ketchup separately.

onions, red onion, olive oil, kosher salt, fresh coarse ground black pepper, balsamic vinegar, ketchup, ketchup, chipotle chilies, adobo sauce, balsamic vinegar, burgers, ground beef, coarse kosher salt, cheddar cheese, muffins, tomatoes, fresh spinach leaves

Taken from www.food.com/recipe/cheddar-burgers-with-balsamic-onions-and-chipotle-ketchup-312028 (may not work)