For the sauce:
1/2 cup unsalted butter
1 small onion, diced
2 cloves garlic, minced
2 cups whole grain mustard
1/2 cup IPA beer
2 teaspoons Worcestershire sauce
2 tablespoons light brown sugar
1/4 teaspoon cayenne pepper
pinch of salt
For the sandwiches:
6 uncooked bratwurst links
1 12-ounce beer
1 onion, thinly sliced
6 pretzel buns, split and toasted
for the red cabbage sauerkraut
1/2 head red cabbage, thinly sliced
2 tablespoons olive oil
1/3 cup garlic, minced
2 teaspoons caraway seeds
2 teaspoons yellow mustard seeds
1 cup cider vinegar
For the Sauce: In a small saucepan over medium heat, melt the butter. Add the onions and lower the heat to medium-low. Sauté the onions, stirring occasionally for 5 minutes or until tender. Add the garlic and cook for 20 seconds more. Stir in the mustard, beer, Worcestershire sauce, brown sugar, cayenne pepper, and salt. Simmer for 15–20 minutes until slightly thickened. Set aside.
For the Red Cabbage Sauerkraut: In a large saucepan, heat olive oil over medium heat. Add the garlic and cook until fragrant but not browned, about 1–2 minutes. Add the cabbage, caraway seeds, mustard seeds, and vinegar to combine. Lower the heat to low and continue to cook for about 10 minutes. Transfer the sauerkraut to a bowl and season with salt and pepper to taste. Serve warm or chilled. This will keep in your refrigerator for up to three days.
For the Sandwiches: Set up your grill for 2-zone cooking. For a charcoal grill, light a charcoal chimney, and when the edges of the charcoal at the top of the chimney begin to ash over, dump the pile of hot coals onto only one side of the grill to form your hot zone (direct cooking). The other empty side forms your cool zone (indirect cooking). For a gas grill, turn on the burners on only one side to form the direct zone. The other side forms your indirect zone.
Place the bratwurst, beer, and sliced onion in a disposable aluminum half-pan. When the grill is ready, place the pan over the direct heat and bring to a boil.
Move the pan over to the indirect side of the grill and close the grill lid. Simmer for 8–10 minutes or until the sausages reach an internal temperature of 160°F. Drain and discard the beer mixture.
Grill the bratwurst directly on the grates over indirect heat with the lid closed, 6-8 minutes or until browned, turning occasionally.
Assemble by placing a brat on the toasted pretzel bun, slathering on the IPA Mustard BBQ, and topping with a helping of the Quick Red Cabbage Sauerkraut.