1. In a medium saucepan, combine cherries, sugar, vanilla bean, and 2 tablespoons water. Simmer cherries, stirring frequently until they are very soft, 5 to 7 minutes. Using a slotted spoon, transfer cherries to a heatproof jar; set aside.

2. Return juice to a high simmer over medium-high heat until reduced to 3/4 cup, 9 to 11 minutes.

3. Remove vanilla bean; stir in lemon juice. Pour syrup over cherries. Let cool completely, uncovered at room temperature, about 45 minutes. Cover with a lid; refrigerate until cold, about 35 minutes. Serve with ice cream. Will keep in refrigerator, covered, up to 2 weeks.