Separate 5 eggs: use all 5 yolks and 3 whites (discard 2 whites). Gently beat the eggs until just combined, being careful not to create bubbles.

Warm the whole milk and sweetened condensed milk in a saucepan (do not boil). Once warm, remove from heat and gently stir in the beaten eggs, mixing slowly to avoid bubbles. Strain the mixture several times through a fine mesh sieve to remove any lumps and ensure a smooth texture.

For the caramel: Add the sugar and a little water to a pan. Stir constantly until the sugar turns a deep amber color, then add a small amount of fresh lemon juice.

Pour the caramel into your molds (glass baking dishes work well). Then pour the egg and milk mixture over the caramel. If there are any bubbles on the surface, skim them off.

For steaming: Bring a suitable amount of water to a boil. Place a towel in the bottom of the steamer tray. Arrange the molds in the tray and cover with a lid (place a towel under the lid to prevent condensation from dripping onto the flan).

Steam the flan for 20 to 30 minutes over medium-low heat (adjust the time depending on the size of your molds). After steaming, insert a toothpick into the flan; if it comes out clean, the flan is done.