Wash the Brussels sprouts and dry them thoroughly.
Cut the nubby ends off of the Brussels sprouts and halve them. If your Brussels sprouts are particularly large, you can quarter them instead.
Heat a pan over medium to medium high heat and add some vegetable oil. Add the Brussels sprouts to the pan and cook them for 20 minutes until they are browned and crispy throughout. Stir occasionally. You should try not to overcrowd the pan if you want the Brussels sprouts to be nice and crispy. We generally cook the Brussels sprouts in batches or use multiple pans.
Mix the ingredients for the honey mustard sauce and set the sauce to the side.
When the Brussels sprouts are done cooking, let them cool for a few minutes then coat them in the honey mustard sauce. Top the Brussels sprouts with pickled onions and serve.