Step 1Cut plums in half and remove pits. Place plum halves, water and sugar in saucepan and bring to boil. Reduce heat and simmer until fruit is soft enough to pass through sieve, 5 to 10 minutes. Cool, then cover and chill several hours or overnight.
Step 2Press cooked plums through sieve or food mill. Stir in cassis and lime juice. Freeze in ice cream maker according to manufacturer's instructions.