Ingredients

• 2 lb. ground beef
• ¹⁄₄ cup minced yellow onion
• 2 tsp. minced fresh thyme
• 1 tsp. ground black pepper
• 1 tsp. minced fresh rosemary
• ¹⁄₄ tsp. ground coriander
• ¹⁄₄ tsp. ground fennel seed
• ¹⁄₈ tsp. cayenne
• 1 egg, lightly beaten
• 2-3 tbsp. melted duck fat, at room temperature (optional)
• Kosher salt, to taste
• 4 hamburger buns, toasted

Instructions

1. In a large bowl, gently mix together the beef, onions, thyme, pepper, rosemary, coriander, fennel, cayenne, egg, and fat. Season with salt. Divide the meat into 4 portions; shape them into 1"-thick patties. Wrap patties in plastic wrap; refrigerate until cold. This will help to firm them up, as they're moister than most burgers owing to the addition of the duck fat and the egg.
2. Prepare a medium-hot charcoal fire or heat a gas grill to medium-high (or heat a tablespoon of canola oil in a large cast-iron skillet over medium-high heat). Cook burgers, flipping once, until cooked to desired doneness, about 12 minutes total for medium rare. Serve on buns.