English mustard is a very spicy and pungent yellow mustard. Use the powdered variety in tins for cooking and the prepared variety in jars as a condiment.
English mustard contains three primary ingredients: ground mustard seed for flavor, tumeric for color, and flour for bulk. Generally the mustard seed is a combination of ground and sifted brown and white mustard.
English mustard can serve two purposes in cooking. Most commonly mustard adds flavor and spice. English mustard can also act as a emulsifier (i.e. it keeps immiscible fluids like water and oil dispersed together).
Use either Chinese or Dijon mustard as direct substitutes for English mustard, as they both provide similar flavor and spice. Try making your own variety of English mustard for specific purposes (e.g. leave the turmeric out to remove the intense yellow color). Substitute another hot constituent such as cayenne pepper or wasabi if the mustard flavor isn't to your liking. If you need an emulsifier but don't want to add flavor, try using soy lecithin.