In a pot, combine 1/2 cup sugar (about 120 grams) with 1/3 cup water (about 100 ml) and cook on the stove until the sugar turns golden. Add lemon juice, wait until the sugar turns amber, then immediately turn off the heat. Add the remaining 1/4 cup water (about 70 ml) and stir gently. Pour the caramel into 15 plastic containers.

Gradually beat 10 egg yolks and 4 egg whites in one direction (gently to avoid creating air bubbles), then add 1/4 cup sugar (about 50 grams) and vanilla extract, and mix until fully dissolved.

Warm 2 cups of whole milk (do not boil) and slowly pour it into the egg mixture, stirring gently in one direction as you pour.

Strain the egg and milk mixture through a sieve (once or twice) to remove air bubbles (to prevent the flan from having holes).

Pour the mixture into the plastic containers with the prepared caramel, cover, and place in a steamer.

Steam for about 15-20 minutes on very low heat. You can test if the flan is done by inserting a toothpick; if the flan sticks to the toothpick, it needs a little more steaming.