Cheddar Burgers with Balsamic Onions and Chipotle Ketchup

Name: Cheddar Burgers with Balsamic Onions and Chipotle Ketchup
Yield: 4 servings
Ingredients: 1 1 pound red onions, cut crosswise into 1/3- to 1/2-inch-thick rounds; 1 Olive oil; 1 3/4 teaspoon coarse kosher salt; 1 1/2 teaspoon coarsely ground black pepper; 1 2 tablespoons balsamic vinegar; 1 1 cup ketchup; 1 1 1/2 teaspoons chopped chipotle chiles from canned chipotles in adobo* plus 2 tablespoons adobo sauce from can; 1 2 teaspoons (or more) balsamic vinegar; 1 2 1/4 pounds ground beef (15% to 20% fat); 1 Coarse kosher salt; 1 6 thick slices sharp cheddar cheese; 1 6 large English muffins or hamburger buns, split, cut sides grilled; 1 6 tomato slices (optional); 1 2 cups fresh spinach leaves

From the kitchen of Carly

Charred red onions caramelized with balsamic vinegar meet smoky chipotle ketchup on juicy cheddar burgers. The onions stay intact on the grill, getting tender and sweet while developing dark, crispy edges that make every bite count.

Prep: n/a
Cook: n/a
Total: n/a
Servings: 4
Difficulty: medium

Ingredients

4 servings

11 pound red onions, cut crosswise into 1/3- to 1/2-inch-thick rounds
1Olive oil
13/4 teaspoon coarse kosher salt
11/2 teaspoon coarsely ground black pepper
12 tablespoons balsamic vinegar
11 cup ketchup
11 1/2 teaspoons chopped chipotle chiles from canned chipotles in adobo* plus 2 tablespoons adobo sauce from can
12 teaspoons (or more) balsamic vinegar
12 1/4 pounds ground beef (15% to 20% fat)
1Coarse kosher salt
16 thick slices sharp cheddar cheese
16 large English muffins or hamburger buns, split, cut sides grilled
16 tomato slices (optional)
12 cups fresh spinach leaves

Instructions

Prepare barbecue (medium-high heat): Arrange onion rounds on baking sheet. Brush with oil; sprinkle with 3/4 teaspoon coarse salt and pepper. Transfer onion rounds (still intact) to grill rack; close cover. Cook until grill marks appear, about 4 minutes per side. Reduce heat or move onions to cooler part of grill. Close cover; cook until onions are tender, about 10 minutes. Transfer to medium bowl. Toss with vinegar. DO AHEAD: Can be made 3 days ahead. Cover; chill.
Mix ketchup, chiles, adobo sauce, and 2 teaspoons vinegar in small bowl. Season with salt and more vinegar, if desired. do a h e a d Can be made 3 days ahead. Cover and chill.
Shape beef into six 1/2-inch thick patties. Sprinkle patties on both sides with coarse salt and pepper. Prepare barbecue (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. Place muffin bottoms on plates; spread with ketchup. Top with burgers, tomatoes, if desired, spinach, and muffin tops. Serve, passing remaining ketchup separately.
*Dried, smoked jalapeños in a spicy tomato sauce called adobo; available at some supermarkets and at specialty foods stores and Latin markets.