1/4 tsp red chili flakes (more if you like a lot of heat)
Set the oven to 425F.
Wash and dry both oranges. Remove the rind of 1 orange using a sharp paring knife, making sure to avoid as much of the pith, that bitter white layer, as possible.
Next, juice the orange. Zest the second orange and set the zest to the side.
Chop the bacon into bite size pieces and cook in a cast iron pan over medium high heat until you have crispy bacon pieces. Remove the crispy bacon pieces and place on a towel lined plate. Pour the bacon fat into a small bowl or jar and set aside.
Wash and dry the brussels sprouts and trim the ends and halve them.
Place the brussels, orange rind and juice, 6 tbsp bacon fat (or whatever amount your bacon has rendered if less than that), chili flakes and maple syrup back into the cast iron skillet or onto a baking sheet.
Season with salt and pepper and place in the oven. Roast for about 40 minutes, flipping halfway through, until the brussels are nice and crispy.
Finish by adding the red wine vinegar and orange zest and bacon pieces. Toss everything together and serve.