Serve this tangy condiment with chicken or turkey. It also complements the flavors of a spicy curry.
Combine all the ingredients in a heavy nonaluminum sauce pan. Bring slowly to a boil then reduce the heat and simmer for about 10 minutes, or until the rhubarb and apple are very soft but still hold their shape. Do not allow them to turn into mush. Taste and adjust seasonings. Cool and chill before serving.