This hot sauce gets its heat from spicy Scotch bonnet chilies. If you can't find those, habanero chilies are a good substitute. To keep your fingers from being coated in spicy capsaicin, use the chilies' stems as a sort of handle while slicing the sides from the center seed pod. A quick blanch in boiling water tames the chilies' spiciness, but won't affect their subtle fruity flavor. Refrigerated in an airtight container, the hot sauce will keep for up to two weeks.
Don’t use Dijon mustard in place of the yellow mustard. Along with ground turmeric, plain yellow mustard gives the sauce its vibrant yellow color.