In a large bowl mix Dijon mustard, honey, mayonnaise, olive oil, salt, and pepper. Add the broccoli slaw and mix with the dressing. Refrigerate for 30 minutes.
Grill the bratwurst over medium-low heat, turning to brown on all sides for about 20 minutes or until fully cooked (the internal temperature has reached 160 degrees F.). (You can also toast the buns by placing them cut-side down onto the grill until lightly toasted).
Place the brats onto the buns and top with broccoli slaw.