01 - Preheat grill to medium-high heat, approximately 400°F.
02 - Toss sliced bell peppers and onions with olive oil, salt, and black pepper until evenly coated.
03 - In a small bowl, whisk together Dijon mustard, honey, apple cider vinegar, and BBQ sauce until smooth and well combined.
04 - Place beef sausages on the grill and cook for 10 to 12 minutes, turning occasionally until browned and cooked through with an internal temperature of 160°F.
05 - Add seasoned peppers and onions to the grill using a grill basket or foil tray. Cook for 8 to 10 minutes until tender and slightly charred, stirring occasionally.
06 - During the final 2 minutes of grilling, brush sausages generously with the mustard glaze, turning to coat evenly and allow the glaze to caramelize slightly.
07 - Serve sausages hot, topped with the grilled peppers and onions. Drizzle with any remaining glaze if desired.