01 - In a small mixing bowl, combine the finely ground coffee, brown sugar, smoked paprika, chili powder, garlic powder, onion powder, and cayenne pepper. Stir until evenly blended.
02 - Divide the ground beef into 4 equal portions and gently shape each into a patty slightly wider than the burger buns. Season both sides generously with kosher salt, black pepper, and the prepared coffee rub, pressing the seasoning gently into the meat to adhere.
03 - In a small saucepan, combine the ketchup, apple cider vinegar, brown sugar, Worcestershire sauce, liquid smoke, smoked paprika, garlic powder, black pepper, and salt. Set over medium-low heat and simmer for 5 to 7 minutes, stirring occasionally, until the sauce thickens. Remove from heat and set aside.
04 - Preheat a grill or grill pan to medium-high heat. Place the seasoned patties on the grill and cook for 4 minutes. Flip the patties, top with cheddar cheese if desired, and continue grilling for another 3 to 4 minutes for medium doneness or to your preferred internal temperature.
05 - Place the burger buns cut-side down on the grill for about 1 minute until lightly toasted and golden.
06 - Spread a generous layer of smoky BBQ sauce on the bottom bun. Layer with lettuce, the coffee-rubbed burger patty, sliced tomato, red onion, pickles, and additional sauce if desired. Cap with the top bun and serve immediately while hot.