There is a good reason why Dijon mustard first originated in the region of its namesake city. Here, Ancient Roman methods ensured that grapevines where grown alongside mustard, which would enrich the soil and provide essential nutrients such as phosphorus.
Soak the mustard seeds together with the white wine and white wine vinegar overnight in the fridge.
The next day, pour the seeds and liquid into the jug of a blender and add 1 tsp (10g) salt. Then blend as smooth as possible, but no longer than 2 minutes so that the mustard seeds don’t heat up, which would affect the colour and flavour. Pass the blended mustard through a fine sieve, store it in an airtight jar and refrigerate it overnight to let the flavours develop. It will change dramatically in aroma and heat over the course of a few hours, so don’t skip this step before consuming.