By Robin Weirs via Heston Blumenthal
275g Black Mustard Seeds
225ml Red Wine Vinegar
1 teaspoon of the four spice mix (cinnamon, mace, cloves and allspice)
3 teaspoons Sea Salt
1 teaspoon ground Black Pepper
1] Mix all the ingredients together in a glass bowl, cover and let sit for 48 hours.
2] Blend in a food processor until the seeds are coarsely ground.