The authors of Wicked Good Burgers are very clearly barbecue experts, and this recipe incorporates all of their skills into a brisket burger. Seasoned with a unique barbecue rub and topped with a pit sauce for the finish, this concoction had us wanting to make a lot more burgers out of brisket.
Mix all of the spices together and store in an airtight container for up to 1 month.
Combine all of the ingredients together in a saucepan and simmer gently, whisking occasionally, for 30 minutes.
In a medium-sized bowl, mix the ingredients thoroughly with a rubber spatula. Cover with plastic and refrigerate. Bring to room temperature before using.
Place the onion slices in a medium, stainless steel mix bowl. Add the coriander, cumin, and red pepper flakes and toss to distribute. In a small saucepan over medium heat, bring the vinegar and water to a boil. Add the sugar and stir until dissolved. Remove from the heat and pour over the onions. Mix well and season with a generous pinch of salt. Let cool to room temperature. Transfer to a jar and refrigerate for up to 1 week.
Clean the grill grate of a kettle grill well with a stiff wire brush. Build a hot charcoal fire on 1 side. Leave the other side empty. This provides a cooler zone to finish cooking the burger. While the grill is heating, prepare the patties. Shape the ground beef into 6 square patties that are slightly larger than the bread and a little thicker around the edges than in the center — about 1 inch on the edges and ¾ inch in the middle. The center of the burger will expand during the cooking process and result in an even thickness. Don’t overwork the meat or pack it tightly. The loose consistency may make the grilling process bit more challenging, but it yields a super-tender burger.
Sprinkle 1 tablespoon of the Basic BBQ Rub on both sides of each patty. Grill for 2 minutes per side, uncovered. Carefully move patties to the cool side of the grill, baste generously with Pit Sauce, and cover the grill. Let patties cook 2 to 3 minutes for rare (125 degrees internal temperature), 3 to 4 minutes for medium-rare (130 degrees), or 4 to 5 minutes for medium (135 degrees).
Remove the burgers from the grill and rest on a platter, loosely tented with foil. Lay the bread slices on the grill just long enough to get a light char, a minute or so. Using tongs turn the bread over and char the other side. Remove and brush 1 side of each slice with softened garlic butter.
Place a patty on one buttered piece of toast, heap generously with onions, and lay another piece of toast on top.
Slice in ½. Repeat for the remaining burgers. Serve with lots of napkins.