In a large pot over medium heat add the oil and garlic, sauté for a minute or two, then add the halved Brussels sprouts.

Sprinkle with salt and pepper, and continue to cook the sprouts, stirring frequently.

Once, the Brussels have started to brown, pour in the Guinness and braise the brussels with the Guinness, once the steam has settled, add in the mustard and mix well to combine.

Keep stirring until the brussel sprouts are soft and browned, and the Guinness has reduced and formed a roux like substance with the mustard.