I have a recipe for Cherry Salsa- you could maybe substitute the rhubarb:
1 1/3 cups frozen unsweetened tart cherries
1/4 cup coarsely chopped dried tart cherries
1/4 cup finely chopped red onion
1 tablespoon seeded and chopped jalapeños (see note)
1 clove garlic, peeled and finely chopped
1 tablespoon chopped fresh cilantro, or 1/2 teaspoon dried cilantro
1 teaspoon cornstarch
Coarsely chop frozen tart cherries. Let cherries thaw and drain, reserving 1 tablespoon cherry juice. When cherries are thawed, combine drained cherries, dried cherries, onion, jalapenos, garlic and cilantro in a medium saucepan; mix well. Combine reserved cherry juice and cornstarch in a small bowl; mix until smooth. Stir into cherry mixture. Cook, stirring constantly, over medium-high heat until mixture is thickened. Let cool.