In a large mixing bowl, combine the peaches with 1/4 cup of sugar and the lemon juice. Cover and refrigerate for a couple of hours, preferably all day.
Puree 1 1/2 cups of the peaches, saving the rest to mix in after you churn the ice cream. In a large mixing bowl, combine the puree with the buttermilk and vanilla; set aside.
In a medium saucepan set over medium heat, combine the remaining sugar, heavy cream, corn syrup, and salt. Heat until warm.
In a small mixing bowl, whisk together the eggs. Slowly pour the warm mixture into the eggs, whisking constantly. Go really slow so you don’t scramble them!
Gradually pour the mixture back into the saucepan. Constantly whisk over medium heat until the mixture thickens and reaches 165 degrees Fahrenheit (74 degrees Celsius).
Pour the mixture through a mesh sieve set over the bowl with the puree, buttermilk, and vanilla.
Whisk the mixture to bring it to room temperature. I generally set my bowl over an ice bath to cool the base down as quickly as possible.
Cover and refrigerate for at least 2 hours, preferably overnight (see notes).
Remove the ice cream base from the refrigerator and pour it into a prepared ice cream machine or attachment bowl. Freeze according to the manufacturer’s instructions (about 25 minutes).
When the ice cream is firm, stir in the diced peaches and place it in a freezer-safe container. Freeze for 2-4 hours before serving.
Notes
-The longer you let the ice cream base chill in the fridge, the more flavorful and intense the vanilla flavor will be.You don't have to add the corn syrup, but it helps keep the mixture extra creamy without turning icy after a few days in the freezer.-I have both the KitchenAid attachment bowl and a Cuisinart ice cream maker. I've found that the Cuisinart produces a thicker, creamier ice cream.-Try adding 1/2 tsp ground cinnamon + 1/2 cup crushed gingersnaps, Biscoff cookies, or baked pie crust!STORE the Peach Buttermilk Ice Cream completely covered in an airtight container such as an old ice cream tub, a special plastic container for homemade ice cream, or a loaf pan.If using a loaf pan, press a piece of plastic wrap or wax paper firmly on top of the ice cream before sealing the entire top with plastic wrap. This extra layer helps prevent freezer burn and keeps the ice cream fresh.When ready to serve, let it sit at room temperature for a few minutes to soften slightly. Avoid refreezing melted ice cream, as it will affect texture and consistency.