- First prepare the leeks by trimming their ends from top to bottom and rinse well to remove dirt.
- Now in a large sauce pan, place the leeks and cover with lightly salted water. Boil gently and let it simmer for 4-5 minutes or until tender.
- With a slotted spoon, carefully remove the leeks and arrange on a shallow serving dish.
- Reserve the liquid and cool it. Blend cornstarch with cooled reserved liquid and keep cooking until sauce thickens, add in the sugar.
- Now in a separate bowl, beat egg yolk with lemon juice and mix in the prepared cooled sauce. Again cook on low heat until sauce is thick but make sure not to over cook as this will curdle the sauce.
- As the sauce thickens, remove from heat, add seasonings and leave it to cool.
- Then pour the sauce over leeks and serve.