1. Combine egg yolks, sugar, and zest in a medium bowl and beat together until creamy.

2. Heat the milk and cream in a saucepan at about medium-high heat, preferably by placing in a larger pot filled with water, as this prevents the milk mixture from boiling.

3. Once the milk mixture is warm, temper the egg mixture by scooping small amounts of the milk and gradually adding to the eggs, stirring with each addition.

4. After adding about 3 cups of the milk to the eggs, pour the tempered egg mixture into the saucepan with the remaining milk.

5. Stir for about 5 minutes until thickened. The custard will visibly stick to the back of a wooden spoon.

6. Cover and chill in refrigerator for at least 4 hours.

7. Strain custard with a fine mesh strainer.

8. Right before churning, add lime juice and stir.

9. Freeze according to ice cream maker instructions.