In a pan, mix water and sugar until there is no lump.
Heat and wait until it boils then turn the heat to simmering mode.
Simmer until the caramel is thick.
Cool slightly and transfer to aluminum moulds.
Mix well the egg yolk, condensed milk and evaporated milk by hand.
Then add vanilla and lemon juice.
Use wooden spatula and mix gently until well combined.
Strain the mixture and gently pour on to the prepared moulds with caramel.
Fill only until 3/4 of the moulder.
Cover with aluminum foil and place the moulds on a larger baking pan half filled with very hot water.
Bake at 350 or 180 for 1 hour.
Cool and then set aside in the fridge.
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.