- In saucepan over medium-high heat, bring rhubarb, sugar and water to boil, stirring occasionally; reduce heat and simmer, covered, for 3 minutes or until tender.
- Pressing gently on fruit, strain into bowl to make about 1½ cups juice; set rhubarb aside.
- Return juice to saucepan.
- Dissolve cornstarch in liqueur, whisk into juice.
- Cook over medium heat, whisking constantly, for 3 minutes or until thickened.
- Stir in any whole pieces of rhubarb.
- Serve warm or at room temperature.