In a medium saucepan over medium to medium-high heat, stir together all sauce ingredients. Let mixture come to a boil and then turn heat down to medium-low and let simmer until rhubarb is broken down but chunks still remain. This should take 10 to 15 minutes, depending on the tenderness of the rhubarb.
Taste test the sauce while it is simmering. Add more sugar if you like a sweeter sauce. Add more water if you'd like a thinner sauce. If you'd like a little more color to your sauce, stir in a drop or two of red food coloring.
Remove pan from heat and let cool completely. Store in an airtight container in the fridge for up to 1 week. Store in a freezer-safe container in the freezer for up to 6 months.
