What types of sauces would pair well with boiled pork knuckles? I'm going to be boiling some pork knuckles. What type of sauce would be a good pairing?

I am guessing that because pork knuckles are fatty, the sauce should tend to be sour or pepper-ish to balance out the fatty taste?
One traditional accompaniment for pork is apple sauce. This follows the convention that a fruity sauce cuts through the fattiness of meat - duck a l'orange is another example.

Apple sauce is easy to make - just taking a cooking apple, chop it up, stew it down with a little water, then stir in some sugar and butter to taste.