Sweet caramelized onions grace these juicy burgers, which are filled with a double hit of onion: red and green.

2  lb. ground beef chuck
1/2  cup finely chopped red onion
1/3  cup sliced green onions
3/4  teaspoon salt
1/2  teaspoon freshly ground pepper
4  garlic cloves, minced
6  onion sandwich buns, split
Caramelized Onions (recipe follows)

1. In large bowl, combine ground beef, red onion, green onions, salt, pepper and garlic; mix well. Shape mixture into 6 (4-inch) patties. Place on large plate. Refrigerate 30 minutes or up to 2 hours to blend flavors.

2. Heat grill. Place patties on gas grill over medium heat or on charcoal grill 4 to 6 inches from medium coals. Cook 8 to 10 minutes or until no longer pink in center, turning once. Serve burgers in buns; top with Caramelized Onions.

6 sandwiches

PER SANDWICH: 575 calories, 30 g total fat (11.5 g saturated fat), 35 g protein, 41.5 g carbohydrate, 95 mg cholesterol, 760 mg sodium, 4.5 g fiber

Caramelized Onions

2 tablespoons butter
1 tablespoon vegetable oil
2 lb. onions, halved, sliced
1/4 teaspoon salt
1/8 teaspoon freshly ground pepper
1/4 teaspoon sugar
3 tablespoons balsamic vinegar

1. Melt butter in large skillet over medium heat. Add oil and onions; stir to coat onions with butter mixture. Cover; cook 5 minutes or until onions begin to wilt.

2. Uncover; stir in salt, pepper and sugar. Cook over medium to medium-low heat 8 to 10 minutes or until onions are golden brown, stirring occasionally.

3. Add vinegar; stir to scrape up browned bits from bottom of pan. Serve warm. (Onions can be made up to 2 days ahead; cover and refrigerate.)