1/3 cup Colman's dry mustard
1/3 cup cider vinegar
2 teaspoons yellow mustard seeds
1/2 cup beer or water
2 tablespoons minced pickled jalapenos plus 2 tablespoons jalapeno pickling liquid
1 1/2 tablespoons molasses
1 tablespoon minced onion
1/2 teaspoon salt
In a small bowl, mix the dry mustard and vinegar until a smooth paste forms. Stir in mustard seeds; cover, then let the mixture sit at room temperature for several hours.
Transfer the mustard mixture to a small, heavy saucepan. Add remaining ingredients and warm over medium-low heat. Cook the mixture slowly, stirring frequently, until thick, about 30 minutes. Cool to room temperature.
Transfer mustard to a small jar and refrigerate for later use. The mustard keeps for up to 2 weeks. Use it as you would any other mustard.