http://www.gourmet.com/food/2009/05/rhubarb-mustard

Rupa’s Rhubarb Mustard

3/4 cup yellow mustard seeds
1/2 cup brown mustard seeds
1/2 teaspoon fenugreek seeds
3 cups rhubarb cut into 1/2-inch pieces
1/2 cup sugar
Just under 1 3/4 cup vinegar (cider vinegar, mostly likely)
1/2 teaspoon salt

Grind the mustard and fenugreek seeds into a fine powder, leaving some
portion of the yellow mustard seeds whole. Put everything in a wide
pot and cook over medium heat until the rhubarb is helplessly soft.
Add a splash of sweet wine at the end if you want to; run it though
the coarse disc of a food mill if you like things smooth rather than
chunky. Process 15 minutes in a boiling water bath if you want to keep
it on the shelf.

Author's Note: Cooking mustard tends to mellow it, so in Rupa’s recipe
the rhubarb sourness is about an even match for the mustard heat. You
might want something with more kick to it, in which case you can stew
the rhubarb first and then simmer it with the vinegar and mustard for
just a few minutes.

--
I love cooking with wine.
Sometimes I even put it in the food.