It used to be that there were a very few mustards in common usage: the dry stuff and the ever-present yellow bottle of prepared mustard. Not anymore. It's not usual to have dozens of mustards vying for your attention. But the ultimate basic choice remains the same: If your recipe calls for prepared mustard, AKA the wet stuff, can you use dry mustard.
The answer is not quite as simple as the question.
Yes, you can substitute dry mustard, but only after you prepare it, that is, add liquid to the dry stuff.
Granted, most of us have some sort of mustard in the refrigerator, or buried deep in a cupboard, just waiting for the next cookout. Who has mustard powder in the pantry but no mustard in the fridge? Not even a forgotten squeeze bottle of French's Yellow somewhere way in the back? Are you a minimalist? A compulsive fridge cleaner? The advantage of mustard seed or ground mustard is that it takes up so little space.
Mustard powder is ground up mustard seeds, and it's what gives prepared mustard its pungency, its hotness level. You could mix a teaspoon of mustard powder with two teaspoons of water to make a very simple mustard. It'll be hot but probably quite bitter. You can do better.
If you have a recipe that calls for a tablespoon of prepared mustard, start with a teaspoon of mustard powder, add a teaspoon of water and a teaspoon of vinegar.
A nice wine vinegar provides an intriguing taste, but any vinegar will do in a pinch, even boring wite vinegar. Stir into a paste in a nonmetallic bowl and let it sit at room temperature for at least 30 minutes. The acid in the vinegar helps to mellow out the heat of the mustard.
You could also add a teaspoon of sugar, or less, depending on your taste, or sweeten your homemade prepared mustard with honey.
If you need more than a tablespoon, combine the following ingredients in a nonmetallic bowl: Avoid the metal because it may interact with your ingredients and leave an unpleasant aftertaste.
- 4 teaspoons mustard powder
- 1 tablespoon water
- 1 tablespoon white wine vinegar
- 2 teaspoons honey
- 1/4 teaspoon salt
Stir the mixture into a paste and let it sit for about an hour. It'll make about 1/4 cup.
Note that while they will function in a pinch, these techniques are only mustard shortcuts. The best homemade mustard starts with whole mustard seeds. Here's a recipe for making homemade Dijon-style mustard.
You can spice up your ground mustard by adding herbs or spices to your mustard seeds and grinding the entire concoction in a coffee grinder or using a mortar and pestle. You will still need a liquid to make the prepared mustard, though. Swap out wine for water for a creamy dijon, or add a pinch of wasabi or horseradish to provide heat, Really, the flavor you want is up to you.