3 cheddar balsamic onions chipotle Recipes

red onion , cut crosswise into 1/3 to 1/2 inch rounds, olive oil, kosher salt, fresh coarse ground black pepper, balsamic vinegar, ketchup, chopped chipotle chilies , from canned chipotle chilies in adobo, adobo sauce , from can, balsamic vinegar, lean ground beef (15%-20% fat), coarse kosher salt, sharp cheddar cheese (thick slices), english muffins or 6 large hamburger buns, split & grilled, tomatoes, fresh spinach leaves

red onions , cut crosswise into 1/3- to 1/2-inch-thick rounds, olive oil, coarse kosher salt, coarsely ground black pepper, balsamic vinegar, ketchup, chopped chipotle chiles from canned chipotles in adobo * plus 2 tbsp adobo sauce from can, more) balsamic vinegar, ground beef (15% to 20% fat), coarse kosher salt, thick slices sharp cheddar cheese, english muffins or hamburger buns, split, cut sides grilled, tomato slices (optional), fresh spinach leaves