How to temper eggs
Tempering eggs is a critical step in making a custard ice cream base, such as in this recipe. It slowly brings the temperature of the eggs up as they’re cooked. Heat them too quickly and you’ll end up with a scrambled mess.
How it’s done is you heat a milk and cream mixture just until it starts steaming, and then add it in a slow steady stream to the eggs while whisking constantly. After they are combined, you can return the mixture to the stove and continue cooking until thickened. Some eggs may still form lumps as they cook, so straining the mixture before chilling will leave your ice cream base silky smooth.