Take warm water in a bowl and add the mustard seeds to it. Let them soak for half an hour. Now pour in the lemon juice and mix it in. Cover it up and let stand for up to three hours. The best way is to let it remain in the refrigerator overnight. The longer you soak them, the spicier they will get.
Drain off the water and put the seeds in a food processor.Add to it the horseradish and the honey. Start the food processor and make a rough puree out of the ingredients. The extent of blend depends on your personal taste. Some people like it smoother.Season with salt and freshly ground black pepper according to taste.
If you have made more than one time use, find a clean jar with a lid. Preserve the mustard in the refrigerator for later use. It can be used as a simple condiment to liven up meals and tastes heavenly even with simple bread sticks.