In your mixing bowl, add the 1/2 cup of brown mustard.
Next, pour in 2 tablespoons of corn syrup or golden syrup.
Add 4 teaspoons of mustard powder to the bowl.
Add 1 1/2 teaspoons of white vinegar to the mixture.
Incorporate 1 teaspoon of soy sauce into the bowl.
Sprinkle in 1 1/2 teaspoons of sugar.
Finally, add 1/4 teaspoon of cayenne pepper.
Using your whisk, mix all the ingredients together until they are completely combined and smooth.
Transfer your Easy Copycat McDonalds Hot Mustard Sauce into a storage container.