Fresh peach puree transforms a vanilla-base into the perfect warm-weather treat.
In a medium saucepan, heat cream and milk over medium-high until tiny bubbles begin to form around edges of pan, 2 to 3 minutes.
While milk mixture heats, vigorously whisk together egg yolks, sugar, and salt in a large bowl until very thick and pale in color, about 2 minutes. Slowly add hot milk mixture to egg-yolk mixture, whisking constantly. Return mixture to saucepan and place over medium heat. Cook, stirring constantly, until foam subsides and mixture is thick enough to coat the back of a spoon, 5 to 7 minutes. Pour mixture through a fine-mesh sieve into a clean bowl set in an ice bath. Let cool while cooking peaches.
In a medium skillet, heat peaches and 2 tablespoons water over medium-high. Bring to a boil, then reduce heat to medium and simmer, stirring occasionally, until peaches are softened, 10 to 12 minutes. Let cool 5 minutes. Carefully transfer peaches and any accumulated juices to a blender and puree until smooth. You should have about 1 1/2 cups.
Stir peach puree, lemon juice, and vanilla into cooled custard. Cover with plastic wrap and refrigerate until cold, at least 2 hours.
Process mixture in an ice cream maker according to manufacturer's instructions. Serve immediately, or transfer to a loaf pan and freeze, wrapped in plastic, up to 1 week. Let soften at room temperature 15 to 20 minutes before serving.
You can also make this ice cream out of season using thawed frozen peaches.