Cut rhubarb stalks in half lengthwise, then slice crosswise into 1/2-inch-long pieces. Split vanilla bean in half lengthwise and use a paring knife to scrape the seeds and pulp into a medium saucepan. Add vanilla pod, sugar and 2 tablespoons water. Without stirring, bring ingredients to boil over medium heat. Continue cooking for about 8 minutes, swirling pan once in a while, until you have a deep golden brown caramel. Immediately toss in half of rhubarb and all of wine. The caramel will seize up and harden slightly. Reduce heat to medium-low and stir with a wooden spoon, breaking up rhubarb, until it's jammy. Stir in remaining rhubarb and 1/2 cup water. Cook a few minutes, until rhubarb is tender but not mushy. Remove pan from heat and strain rhubarb over a bowl, reserving rhubarb and liquid. Return liquid to pan and bring to a boil over medium-high heat. In a small bowl, whisk together 1 tablespoon water with cornstarch. Whisk cornstarch mixture into boiling liquid and let it return to a bowl, stirring continuously. Reduce heat to medium and cook 2 to 3 minutes, until liquid is shiny and thickened. Pour liquid back into bowl and stir in rhubarb. Cover and chill before serving over ice cream, semifreddo or other dessert.
Note: This recipe must be prepared in advance. From "The Big Book of Outdoor Cooking and Entertaining" by Cheryl and Bill Jamison.