Bechamel sauce is the white sauce made from butter, milk and flour that is typically used in dishes such as lasagne. I was surprised at how well it worked using the dairy-free ingredients. I adapted this recipe from Delia Smith's Classic collection.
The butter is replaced with dairy-free margarine and the milk is replaced with soya milk. I have made this gluten-free by using Dove's gluten-free plain flour.
The vegan cheese is optional, it depends what the sauce is going to be used for and what flavour you want. I sometimes add some ground nutmeg, or a teaspoon of dijon mustard at the end.