On low, heat the half and half, sugar, salt, and egg yolks in a small sauce pan, whisking occasionally until the mixture is hot and thickens slightly.
Allow the mixture to cool to room temperature, then transfer to a blender.
When the mixture is cool, chop the spruce tips well, then add to the blender and puree until very smooth. It takes a bit of horsepower to break down the needles, for the best flavor you really need them finely blended.
When the mixture is pureed, pass it through a fine mesh strainer. If possible, allow the custard to sit in the fridge overnight, which will give a better texture in the finished product. Before spinning, whisk in the lime juice.
Place the spruce custard in the bowl of an ice cream maker and process according to the manufacturers directions. Mine usually takes about 45 minutes. Garnish with a drizzle of the chokecherry sauce.