Preheat oven to 375 degrees.
In a bowl, mix halved brussels sprouts with oil, salt and pepper until all pieces are evenly coated.
Spread coated sprouts on sheet pan and roast for 25 minutes or until browned and caramelized.
While sprouts are roasting, mix together mustard, apple cider vinegar, and honey in a small sauce pot and heat on low.
Continue to heat sauce or reduce sauce until desired taste and texture is reached.
Serve sauce or dip on the side with the roasted brussels sprouts.