Prepare an ice bath; set aside. Split the vanilla bean lengthwise with a sharp paring knife. Gently scrape out all the seeds. Whisk together 1/2 cup sugar with the yolks; set aside. Place the vanilla bean scrapings and pod in a medium saucepan with the cream, milk, and the remaining 1/2 cup sugar and pinch of salt. Bring the milk mixture just to a simmer. Using a measuring cup or a ladle, slowly pour about 1/2 cup of the hot milk mixture into the egg-yolk mixture, whisking constantly. Keep adding milk mixture, about 1/2 cup at a time until it has all been added. Pour mixture back into saucepan, and cook over low heat, stirring constantly with a wooden spoon, until mixture is thick enough to coat the back of a spoon, 3 to 5 minutes. The custard should retain a line drawn across the back of the spoon with your finger. Pour through a mesh sieve into a medium bowl set in the ice bath, discard vanilla bean. Stir occasionally until cooled. Whisk in cherry concentrate and corn syrup or glucose. Cover and transfer to refrigerator until chilled at least 1 hour and up to overnight. Pour into an ice-cream maker and add poached cherries. Process according to manufacturers' instructions until set, but not hard. Transfer the soft ice cream to a plastic container; freeze at least 4 hours and up to overnight.
Combine the cherries, sugar, and black cherry concentrate in a medium saucepan. Cover and place over medium-low heat. Cook, stirring occasionally, until cherries are tender, about 15 minutes. Transfer to an airtight container and refrigerate until chilled, at least 1 hour and up to overnight. Yield: about 3 cups
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