Make Easy English Mustard

I use mustard so infrequently that I found myself buying a jar, using a quarter of it, and then once the six months 'use within' date was up having to throw the rest away. This way is alot less wasteful, both in terms of packaging and product.
YOU WILL NEED
Mustard powder
Boiled water (cooled to room temp)
Salt to taste
METHOD
1) Place the mustard powder and the salt in a bowl.
2) Add the water bit by bit, mixing as you go, to make a smooth (non-lumpy) paste (the paste should drop from a spoon but not be watery).