True Midwesterners will tell you to first plunge the brats in a mixture of beer and onions, poaching them over the fire until just cooked through — a technique that helps them soak up more delicious flavor while keeping them juicy. After that, it's all about getting that crispy char on the exterior, something you'll easily achieve over direct heat. Serve the sliders with plenty of tangy mustard and a cold beer, of course.
Technique tip: Parboil the brats prior to the big game, and simply heat and grill at tailgate to save a step.
Swap options: Use Polish sausage, hot dogs or smoked bologna.
Stir together the onion, thyme, beer, mustard, vinegar, honey and salt in a cast-iron skillet; submerge the bratwurst links in the mixture.2.
Open the bottom vent of a charcoal grill completely. Light a charcoal chimney starter filled with charcoal. When the coals are covered with gray ash, pour them onto the bottom grate of the grill. Adjust the vents as needed to maintain an internal temperature of 350 to 400 F. (If using a gas grill, preheat to medium, 350 to 400 F.)3.
Place the skillet with the bratwurst mixture on unoiled grates in the center of the grill. Grill, covered, until the bratwursts are cooked through, about 30 minutes.4.
Remove the bratwursts from the skillet; set aside. Move the skillet to the perimeter of the grill and cook the onion mixture, uncovered and stirring occasionally, until the mixture thickens, about 20 minutes. Remove from the heat; remove and discard the thyme.5.
While the onion mixture cooks, place the bratwursts directly on oiled grates. Grill, uncovered, and turn occasionally, until browned and crisp, about 10 minutes. Transfer to a cutting board and let cool slightly, about 5 minutes. Slice each bratwurst in half crosswise at an angle.6.
Spoon 2 tablespoons of the onion mixture into each split roll; top with a bratwurst half and a dollop of mustard. Arrange brats on a serving platter.