Caramelized Onion Burgers

• medium onions, sliced↗4
• teaspoons sugar↗2
• tablespoons olive oil↗2
• cup water↗1⁄4
• tablespoon balsamic vinegar↗1
• teaspoon salt, divided↗3⁄4
• lb ground beef↗1
• cup chopped parsley1⁄4
• tablespoons tomato paste↗2
• teaspoons Worcestershire sauce↗2
• teaspoon fresh ground pepper↗1⁄4
• hamburger buns, toasted↗4
• slices tomatoes↗4
• lettuce leaf↗

Step-by-step instructions

1. 1

   Cook onions and sugar in hot oil over low heat 20 to 25 minutes until onion is caramelized, stirring often. Stir in the 1/4 cup water, vinegar, and 1/4 teaspoon of the salt. Set aside and keep warm.

2. 2

   Combine beef, parsley, tomato paste, Worcestershire sauce, 1/2 teaspoon salt, and pepper. Shape into 4 patties.

3. 3

   Grill over medium-hot heat until beef is no longer pink.

4. 4

   Serve on buns with caramelized onions, tomato slices and lettuce.