Grass-fed Beef Burgers with Caramelized Sweet Onions

In a medium sauté pan, heat the butter or oil over medium heat and add the onions. Cook, stirring occasionally, until the onions are deep golden brown, about 15 minutes. Cool the onions completely. (You can do this step up to a day in advance.)

Combine the ground beef with the caramelized onions, Worcestershire, and salt and pepper, and divide the mixture into 6 portions. Roll each portion into a ball and flatten them out to about 3/4-inch thick.

Cook the burgers on a preheated gas or charcoal grill for 6 to 8 minutes to a side, or until a thermometer inserted in the center of the meat reads 155° F. Place a slice of cheese on top of each burger in the last minute of cooking. Remove them from the grill and layer onto buns with lettuce, tomato and your favorite burger condiments.