Prepare the Custard Base: In a medium-sized, heavy-bottomed saucepan, combine the heavy cream, whole milk, granulated sugar, and fine sea salt. Whisk together until the sugar begins to dissolve. Add the egg yolks along with the scraped vanilla bean seeds and pod. Place the pan over low to medium-low heat.
Cook the Custard Slowly: Stir the mixture constantly with a heat-resistant spatula or whisk, making sure it does not boil. The custard will gradually thicken as it warms, reaching about 170°F (77°C). Once you see steam rising and the texture slightly coats the back of a spoon, remove the pan from the heat.
Strain and Flavor the Mixture: Pour the custard through a fine mesh sieve into a clean bowl to remove any cooked egg particles and the vanilla pod. Stir in the peppermint extract and vanilla extract if you’re using that instead of the bean. Add food coloring at this point if desired. Allow the custard to cool to room temperature before covering and refrigerating it for at least 12 hours or overnight.
Prepare the Chocolate Chips: While the custard chills, melt the chopped dark chocolate gently using a double boiler or microwave in short bursts, stirring frequently to avoid burning. Once mostly melted, stir in the coconut oil until smooth and glossy. Spread the chocolate in a thin, even layer on a parchment-lined baking sheet and place it in the freezer to harden completely.
Churn the Ice Cream: Remove the chilled custard from the fridge and discard the vanilla bean pod if used. Pour the mixture into your pre-frozen ice cream maker bowl and churn according to the manufacturer’s instructions until it thickens into soft-serve consistency.
Add Chocolate Chips: Take the hardened chocolate from the freezer and chop it into small, bite-sized pieces. During the last few minutes of churning, add the chocolate bits to the ice cream. If your machine doesn’t allow adding mix-ins during churning, fold them in gently by hand once churning is complete.
Freeze Until Firm: Transfer the ice cream to an airtight, freezer-safe container. Freeze for several hours or until firm enough to scoop. Enjoy your rich, homemade mint chocolate chip ice cream!