Preheat the oven to 325 degrees.
Combine the sugar, water and lemon juice in a heavy-bottomed saucepan.
Heat over medium-low heat. When the sugar begins to melt, lift the pan and gently swirl it to move the sugar.
Continue to swirl the pan periodically until all the sugar has melted and the mixture is a deep amber color.
Pour the caramel into an 8-inch cake pan or flan pan.
In a large mixing bowl combine the eggs, sweetened condensed milk, evaporated milk, vanilla, and salt. Whisk until the mixture is smooth and no traces of egg remain.
Pour the custard through a strainer into the caramel coated cake pan.
Cover the cake pan with foil and place in a casserole dish.
Boil water and pour the water around the base of the cake pan. Fill the casserole dish until the water comes halfway up the cake pan.
Place the casserole dish with the cake pan inside in the oven. Bake for 45 - 50 minutes until the flan is set.
Remove from the oven and remove the cake pan from the water bath. uncover and let cool.
To Unmold the Flan: Place the flan back in the casserole dish and pour hot water around the base of the cake pan - coming up about ¼ of an inch. Let sit for 2 - 3 minutes.
Remove the cake pan from the casserole and place your serving dish on top, serving side down.
Grasping both the cake pan and the serving plate securely, flip the pan and serving platter so that the cake pan is on top.
The flan should pop right out onto the serving platter. If it doesn't plop right out, shake the cake pan to loosen the flan.
Spoon any remaining caramel over the top of the flan.
Garnish with fresh berries and mint if desired. Serve.