Preheat the grill to medium high.: You will hear a steady hiss when the grates are hot enough, and the metal should feel warm if you hover your hand above it briefly. A properly preheated grill sears the exterior quickly, creating a flavorful crust while keeping the inside juicy. If the grates are not hot, the patties will stick and lose moisture. Avoid charring by keeping the heat in a medium high zone and watch for flare ups, gently moving patties if flames spike.
In a medium bowl, using your hands, mix 1 1/2 pounds ground beef, 2 tablespoons BBQ sauce, 1/2 teaspoon garlic powder, 1 teaspoon salt, and 1/2 teaspoon pepper just until combined. Shape into 4 3/4-inch thick patties. Using your thumb, make a well in the center of the patties to prevent bulging.: As you press the mixture, you will feel the texture change from loose to slightly tacky, indicating it has just enough cohesion. The BBQ sauce will add a moist sheen that helps with browning. The shallow well in the center is a tiny trick that keeps the middle from puffing, so the patty stays flat and cooks evenly. Overmixing is a common error, which makes the cooked burger dense, so stop as soon as the ingredients come together. If the patties feel too warm, chill briefly to firm them for easier handling.
Place patties on the grill and cook 4 to 5 minutes. Flip and cook an additional 4 to 5 minutes, or until juices run clear. Top with cheese slices, if desired. Cover the grill and cook until cheese has melted. You can also butter your buns and put on the grill the last minute of cooking if desired.: The first side will develop a deep brown crust and emit a savory aroma as the fat renders. When juices bead on the uncooked surface, that is a cue to flip. After flipping, listen for another satisfying sizzle indicating the second sear. If you add American cheese , it should soften and drape the patty after a minute under a covered lid. Buttered hamburger buns placed briefly on the grill will toast to a golden edge and smell rich and nutty. Avoid pressing the patties with a spatula which squeezes out juices and dries the burger.
While the burgers are cooking combine the ingredients for the sauce in a small bowl. Mix until combined and set aside.: The sauce will come together into a pale, smooth mixture with little flecks of seasoning. Whisking briefly creates a cohesive emulsion so it clings to the bun without sliding off. Taste and adjust the balance if needed, noting that the vinegar should give a faint bright pop against the mayo . A common misstep is overacidifying, which can dominate the flavor, so err on the side of subtlety and add more vinegar sparingly.
Place on buns and top with your favorite toppings to serve.: The final assembly is about contrast and balance. Place the warm patty on the toasted bottom hamburger bun , spoon a little of the sauce so it soaks slightly into the bun, add optional dill pickle relish or cheese, then cap it with the top bun. The ideal bite gives a textural interplay between the soft interior, the crisped edges of the bun, and any crunchy toppings. If the sandwich feels too soggy, next time reduce sauce quantity on the bottom bun or toast the bun a touch longer. Serve promptly so the textures remain distinct.