01 - Preheat your grill to medium-high heat (about 400°F/200°C).
02 - While the grill heats, heat the vegetable oil in a skillet over medium heat. Add the sliced onion and cook, stirring frequently, until softened and golden, about 8 minutes. Add the drained sauerkraut and caraway seeds (if using); stir and cook for an additional 3–4 minutes until heated through. Season with black pepper.
03 - Grill the beef bratwursts, turning occasionally, for 12–15 minutes, or until evenly browned and fully cooked (internal temperature should reach 160°F/71°C).
04 - During the last 2 minutes of grilling, place the buns cut-side down on the grill to toast lightly.
05 - To assemble, place a grilled bratwurst in each toasted bun. Top generously with the warm sauerkraut-onion mixture. Add mustard, ketchup, and pickles as desired. Serve immediately, hot off the grill.