Crack 20 eggs into a large bowl, including both yolks and whites. Gently whisk the eggs in one direction until well combined. Strain the mixture through a fine mesh sieve.

In another bowl, mix the sweetened condensed milk with 1 can of hot water and stir until dissolved. Add 1 can of filtered water and mix well. Slowly pour the egg mixture into the milk, gently stirring to combine. Avoid creating bubbles.

In a small saucepan, add 7 tablespoons of sugar and just enough water to moisten the sugar. Gently swirl (do not stir with chopsticks or a spoon) over low heat until the sugar turns a deep amber color. Add a little more water to keep the caramel from thickening too much. Once it boils up again, remove from heat and pour the caramel into each flan mold. If using glass molds, add the caramel immediately and swirl to coat. If using plastic molds, let the caramel cool slightly before pouring.

Steam the flan over medium heat for about 30–40 minutes (depending on the size of your molds). Occasionally lift the lid to let out steam and prevent water from dripping onto the flan. To check for doneness, insert a toothpick—if it comes out clean, the flan is done. Let the flan cool, then refrigerate until chilled.

To serve, unmold onto a plate and enjoy! You can add a little coffee or crushed ice if you like.