It is very important to always add water to mustard powder and let stand 10 minutes before adding vinegar in recipes if you want to maintain a hot flavour.

Yellow Mustard Powder (YMP) yields a hot taste at the back of the tongue.
Oriental Mustard Powder (OMP) yields a hot taste on the tip of the tongue, and a pungent odour in the nose. Turmeric adds a good flavour and colour to mustard. Recipes can use a blend of YMP and OMP to taste.

3 Tbsp. Bacon Fat 2 Tbsp. Flour 1 Tbsp. Grated Onion ¾ tsp. Mustard Powder 1½ tsp. Salt 1/8 tsp. Black Pepper ¼ tsp. Sugar 2 tsp. Cream Salad Mustard 2 Tbsp. Vinegar 1 C. Water

Melt bacon fat. Stir in flour, add onion, cook slowly for 1 minute. Blend in seasonings, sugar, mustard and vinegar. Add water, continue to stir. Cook, stirring constantly until thickened. Makes 1 C.