½ cup cognac, Hennessy® or apple cider
½ cup Dijon mustard, Grey Poupon®
2 teaspoons fresh tarragon
1½ pounds ground sirloin
2 packages (2 ounces each) onion soup mix, Lipton®
¼ cup cognac, Hennessy®
½ cup cracked black pepper, McCormick®
Lettuce, tomato, red onion
For Cognac-Mustard Sauce, in a small saucepan over medium-high heat, bring cognac to a boil and reduce by half, about 4 to 5 minutes. Remove from heat and let cool. Once cognac reduction has cooled, add to small bowl along with mustard and tarragon. Stir to combine; set aside.
Set up grill for direct cooking over high heat. Oil grate when ready to start cooking.
For burgers, in a mixing bowl, stir to combine ground sirloin, onion soup mix, and cognac. Wet your hands to prevent sticking and form into 4 patties slightly larger than rolls; set aside. Spread cracked pepper on a plate. Carefully press both sides of burgers into cracked pepper; set aside, covered in plastic wrap, and refrigerate if not cooking immediately.
Place burgers on hot oiled grill and cook 4 to 5 minutes per side for medium.
Serve hot on toasted kaiser roll with lettuce, tomato, onion, and a spoonful of sauce.