Creamy-Coffee Ice Cream

Prepare an ice bath; set aside. Stir together espresso powder and hot water in a small bowl; set aside. In a medium bowl, whisk together 1/2 cup sugar with the yolks; set aside.

Split the vanilla bean lengthwise with a sharp paring knife. Gently scrape out all the seeds. Place vanilla bean scrapings and pod in a medium saucepan with heavy cream, milk, remaining 1/2 cup sugar, and salt. Bring milk mixture just to a simmer. Whisking constantly, slowly ladle about 1/2 cup of the hot milk mixture into the egg yolk mixture. Continue adding remaining milk mixture, about 1/2 cup at a time.

Pour mixture back into saucepan; cook over low heat, stirring constantly with a wooden spoon, until mixture is thick enough to coat the back of the spoon, 3 to 5 minutes. The custard should retain a line drawn across the back of the spoon with your finger; stir in reserved espresso mixture. Pour through a mesh sieve into a medium bowl set in the prepared ice bath; discard vanilla bean. Stir occasionally until cooled. Cover with plastic wrap, and chill in refrigerator for at least 1 hour and preferably overnight.

Pour into an ice-cream maker. Process according to manufacturer's instructions until set, but not hard.

Transfer soft ice cream to a metal or plastic container; freeze for at least 4 hours and up to overnight.