1. While the crust is baking, prepare the lemon curd. Whisk egg yolks till beaten well. Add in the sugar, lemon juice, and zest, and beat again.
2. In a heavy-bottomed pot over low heat add in the egg mixture and stir consistently for 10 minutes. You do not want to raise the temperature or rush this process, because the eggs can curdle. You will know the mixture is ready when it has thickened up and has coated the back of the spoon without being runny. Turn the heat off and immediately add the cold margarine/butter, stir to melt.
3. Pour the lemon curd into a container, and place a piece of plastic wrap directly on top of the curd to prevent a film. Then top the container with the lid and let it cool down in the fridge.