Peel, pit, and slice the fresh peaches into 1-inch wedges. Add the peaches, sweetened condensed milk, granulated sugar, fresh lemon juice, and fine sea salt to a food processor. Blend until the peaches break down into small, uniform chunks—you want texture here, not a smooth purée. I find that leaving some peach pieces intact gives the final ice cream a more interesting, natural feel rather than a completely smooth consistency.

Transfer the peach mixture from Step 1 into a large bowl. Pour in the peach soda and stir gently to combine, being careful not to deflate all the carbonation—a little fizz remaining actually helps create a lighter, airier texture in the final product. Let the mixture chill in the refrigerator for at least 30 minutes before churning; I like to chill it for up to 2 hours for best results, as a colder base churns more efficiently.

Pour the chilled peach soda mixture into your ice cream machine and process according to the manufacturer's instructions, typically 20-30 minutes, until the mixture reaches a soft-serve consistency. Transfer the finished ice cream to a freezer-safe container and freeze for at least 4 hours until firm enough to scoop.