The recipe for it comes from Steve of Mr. Steve's Homebrew supplies here in York, PA. He's got some great recipes and this batch of beer came out superb! So in it went.
I've made this mustard several times now. My neighbors love it, the brew club loves it, and my co-workers enjoy it as well!
It's such a simple recipe that I will include it here. Hopefully Saveur doesn't mind!
1- 12 oz bottle of Guinness Extra Stout
1 1/2 cups brown mustard seeds (10 oz)
special note I found it better to use half brown mustard seeds and half yellow mustard seeds
1 cup red wine vinegar
1 TBSP kosher salt
1 tsp freshly ground black pepper
1/4 tsp ground cinnamon
1/2 tsp ground cloves
1/4 tsp ground nutmeg
1/4 tsp ground allspice
Mix all the above ingredients in a glass mixing bowl (or any non-reactive mixing bowl).
You can then put it in a food processor, but I leave it in the same bowl and use my immersion blender to process the mixture. Process it until the seeds are coarsely ground and the mixture thickens, which only takes about 3 minutes.
Mustard schmeared on my homemade rye bread with a good aged white cheddar! What a great grilled cheese this makes!