Peel and dice the peaches into 1/2-inch pieces, then place them in a bowl with xylitol and lemon juice. Stir well to combine and let sit for 30 minutes—this draws out the peach juices and develops the flavor. While the peaches macerate, set up an ice bath by filling a large bowl with ice water; you'll need this to cool the custard base quickly. After 30 minutes, gently mash the peaches with a fork to break them down slightly, creating a chunky peach mixture.
Pour the heavy cream and almond milk into a pot and heat over medium heat until it reaches a simmer—you'll see small bubbles forming around the edges. While the cream heats, whisk together the egg yolks and sea salt in a separate bowl until the yolks are pale and slightly thickened, about 1 minute. Once the cream mixture is hot, slowly add about 1/2 cup of it to the egg yolks while whisking constantly; this tempers the eggs so they don't scramble. Then pour the tempered egg mixture back into the pot of hot cream, whisking continuously to combine.
Continue cooking the custard mixture over medium heat, stirring frequently with a wooden spoon or whisk, until it reaches 170°F on a thermometer and coats the back of the spoon—this takes about 5-8 minutes and ensures food safety. I like to use a thermometer here rather than guessing the consistency, as it guarantees the eggs are pasteurized and the texture is perfect. Immediately pour the cooked custard into a clean bowl set over your ice bath, stirring occasionally for about 10 minutes to cool it down quickly. This rapid cooling stops the cooking process and helps develop a smooth texture.
Once the custard has cooled, stir in the macemented peach mixture from Step 1, then sprinkle the glucomannan over the top and whisk thoroughly to distribute it evenly. Glucomannan acts as a thickening agent and helps create a creamier texture in the final ice cream. Stir in the vodka and vanilla extract—the vodka lowers the freezing point slightly, which keeps the ice cream scoopable even at low temperatures. Cover and refrigerate the entire mixture for at least 3 hours, or preferably overnight, to allow the flavors to meld and the mixture to chill completely.
Pour the chilled mixture into your ice cream maker and churn according to the manufacturer's instructions, typically 20-30 minutes, until it reaches a soft-serve consistency. Transfer the churned ice cream to a freezer-safe container and freeze for 1-2 hours until firm enough to scoop. I recommend slightly softening the ice cream at room temperature for 5 minutes before serving if it's been frozen longer than a few hours—this makes it easier to scoop and brings out the peach flavor.
