Mustard is a hard color to match with but i found a couple of choices:lime greenredaubergineemerald greenwhitepeach pinkHope this works out for you!!
Mustard is a dark yellow color. You can make it by adding a little gray to a lot of yellow. Instead of gray, you may want to add a bit of brown.
American yellow mustard is colored yellow first by its mustard seed which is a very light yellow, or the color of a typical french fry.However, American yellow mustard producers also add the herb powder of the rhizome turmeric to give it the bright yellow color it is known for.
A mustard color
You add water too it..?
When you add a hint of ajinomoto/vinegar /mustard/asophetita
They are substances such as salt, pepper, mustard, chutney or pickle which add flavour to the food
What color change do you see when you added ammonia to mustard?
Purple
Actually a half cup of whole grain mustard (seeds) is equal to a half cup, plus two table spoons of ground mustard. If your recipe calls for mustard seeds and you are using ground, it seems you can add a little more of the ground mustard. To be safe, I would add the same amount first and then add to taste.
mustard brown
yellow