When I was little, my maternal grandmother used to have a pot of rhubarb constantly stewing on the stove when we visited in the summer. Know it had rhubarb, water and sugar, but don't know what else or how much. Do you know?
That is really all you need: rhubarb, a little water (just a few tablespoons because rhubarb has very high water content), and a generous amount of sugar sprinkled over. It doesn't actually take a long time to cook. About 5 - 10 mins over medium heat with lid on.