Melt butter in heavy large saucepan over medium high heat. Add ginger and rhubarb, and saute 2 minutes. Add water, sugar and lemon juice. Bring to boil. Reduce heat and simmer until rhubarb is very tender, stirring frequently, about 15 minutes. Remove from heat and cool slightly.
Scoop ice cream into glass dishes. Spoon warm rhubarb over. Garnish with mint and serve immediately.
c.1996, M.S. Milliken & S. Feniger, all rights reserved