In a medium bowl, combine the black and yellow mustard seeds with the vinegar and 1 1/2 cups of the beer. Cover and refrigerate overnight.
In a medium saucepan, combine the remaining 1/2 cup of the beer with the honey, brown sugar, salt, allspice and turmeric and bring to a boil. Remove from the heat, transfer to a blender and let cool. Add the ground mustard and the mustard seeds with their soaking liquid to the blender and puree. Transfer the mustard to a glass jar. Cover and refrigerate overnight before serving.