In a saucepan, mix the sugar & water. Bring to a boil for a few minutes until the sugar caramelize.
Pour the caramelized sugar into aluminum moulds - you can use any shape: oval, round or square. Spread the caramel on the bottom of the moulds.
Mix well the evaporated milk, condensed milk, egg yolks and vanilla by hand or blender.
Gently pour the mixture on top of the caramel on the aluminum moulds. Fill the moulds to about 1 to 1 1/4 inch thick.
Cover moulds individually with aluminum foil.
Steam for about 20 minutes (the traditional way to make Leche Flan is by open-air steaming on either an open cooking fire or stove top) OR
Bake for about 45 minutes. Before baking the Leche Flan, place the moulds on a larger baking pan half filled with very hot water. Pre-heat oven to about 370 degrees before baking.
Let cool then refrigerate.
To serve: run a thin knife around the edges of the mould to loosen the Leche Flan. Place a platter on top of the mould and quickly turn upside down to position the golden brown caramel on top.