This recipe is based on the one for Pomegranate Rose Sorbet in my cookbook; rose water enhances tart cherries beautifully too. Find tart cherry juice concentrate at Whole Foods, health food stores, or online. If you prefer to use fresh tart cherries, that works wonderfully too. Puree 3 cups of pitted tart cherries (from frozen is fine) and substitute that for the cherry juice concentrate and water. Be sure to use tart or sour cherries rather than sweet cherries for that particular tart cherry flavor. The corn syrup is used to help keep the texture of the sorbet smooth. Find Italian Fabbri Amarena Cherries online.
Combine the cherry juice concentrate, sugar, corn syrup, and water in a small saucepan over medium heat. Cook until the sugar dissolves, stirring occasionally. Add the lemon juice and rose water, and continue to cook for another minute.
Chill the base until completely cold, either in the refrigerator or by placing the base in a zip lock bag immersed in a bowl of ice water.
Process the sorbet in an ice cream maker according your maker instructions. In mine, a Cuisinart, simply freeze the maker bowl in advance.
Freeze the sorbet for at least 24 hours so it hardens properly. Serve scoops in sundae dishes, topped with a few Amarena cherries and their syrup, and chopped pistachios.