In about five minutes, intensely flavored and, perfect for serving with the burger, and smearing on the bun, and even mixing into the beef before cooking.
2 tablespoons tomato paste
2/3 cup beef broth 1/3 cup raisins
2 tablespoons soy sauce
2 tablespoons Dijon mustard
2 tablespoons balsamic vinegar
1 tablespoon Worcestershire sauce
Meanwhile, add tomato paste to skillet and cook over medium heat until paste begins to darken, 1 to 2 minutes. Next add the, raisins, soy sauce, mustard, vinegar, and Worcestershire and simmer until raisins plump, about 5 minutes. Process sauce in blender until smooth, about 30 seconds; transfer to bowl.