Crush the mixture of mustard seeds, coriander seeds and vinegar with a mortar. Add honey and mustard powder, and season to taste with white wine vinegar.
This mustard has a long shelf life when refrigerated.
8 tbsp. mustard seeds, reconstituted in white wine vinegar overnight
½ tsp. coriander seeds
1 large tsp. honey
½ tsp. mustard powder
1-2 tbsp. white wine vinegar