Steamed Pork fillet with leeks

I found this in a book of idiot-proof – only a few ingredients – incredibly healthy – lose-weight recipes. It’s remarkably tasty and simple.
– wash leeks, slice lengthwise and blanch them for a few minutes in boiling water until soft.
– trim a pork fillet of any excess fat and spread all over with a mixture of grain and smooth mustard.
– wrap the mustardy pork in the leeks (see photo left, click on it to zoom).
– steam it for 40 minutes.
– serve with a cold mustard sauce made from two or three different types of mustard mixed with “Petit Suisse” cheese (or fromage blanc) and a little lemon juice.