Combine the heavy cream, coconut milk, ground turmeric, grated ginger, cinnamon, and sea salt in a medium saucepan. Warm the mixture over medium-low heat, whisking occasionally until it becomes hot and fragrant. Do not allow it to boil.

In a separate mixing bowl, whisk the egg yolks together with the powdered allulose until the mixture becomes lighter in color and slightly thickened.

Slowly ladle a small amount of the warm cream mixture into the egg yolks while whisking continuously. Repeat several times until the eggs are gradually warmed, then pour the tempered egg mixture back into the saucepan.

Cook the custard over low heat, stirring constantly with a silicone spatula or wooden spoon until it thickens enough to coat the back of the spoon. Avoid boiling to prevent the eggs from curdling.

Remove the saucepan from the heat and stir in the vanilla extract and freshly grated lemon zest until fully incorporated.

Pour the custard through a fine mesh strainer into a clean bowl if desired for an extra-smooth texture. Allow it to cool slightly, then cover and refrigerate for at least 6 hours or overnight.

Once thoroughly chilled, pour the custard into your ice cream maker and churn according to the manufacturer's instructions until it reaches the consistency of soft-serve ice cream.

Transfer the churned ice cream to a freezer-safe airtight container. Smooth the surface with a spatula, place parchment paper directly on top if desired, cover tightly, and freeze for 2 to 4 hours until firm.

Before serving, allow the ice cream to sit at room temperature for 5 to 10 minutes. Scoop into chilled bowls and garnish with toasted coconut, chopped nuts, fresh berries, or an extra sprinkle of cinnamon if desired.