From: Ball Complete Book of home preserving.

Oktoberfest Beer Mustard:

1 1/2 c Beer
1 c Brown Mustard Seeds
1 c Water
1/2 c Malt Vinegar
1/2 c Brown Sugar
1/4 c Dry Mustard
1 tbsp Onion Powder

1. In a medium sauce pan combine beer and brown mustard seeds; bring to boil over medium/high heat. Remove from heat. Cover and let stand at room temperature until seeds have absorbed most of the moisture.
2. Prepare canner jars and lids
3. In a blender or food processor puree marinated seeds and any remaining liquid until most seeds are well chopped.
4. Transfer mixture to saucepan and whisk in water, vinegar, brown sugar, dry mustard, and onion powder. Bring to boil over high heat, stirring constantly. Reduce to medium heat; boil gently, stir frequently. Reduce by 1/3.
5. Ladle hot mustard into jars leaving 1/4 inch head space. remove bubbles, wipe rim, put lid on and screw lid until fingertip tight. Place jars in canner and ensure they are completely covered with water. Process for 10 minutes in a water bath canner.