Preheat the oven to 325°F.
Caramelize the sugar, corn syrup and water. Immediately pour into a 6-cup shallow flan mold.
Whisk together the eggs, milk, condensed milk, zest, cinnamon, and vanilla salt until well combined.
Pour over caramel.
Set the pan in a roasting pan and fill with HOT water, half way up the flan.
Bake for about 40-50 minutes or until a knife comes out clean when inserted into the middle of the flan.
Cool in the water bath, then refrigerate for at least 2 hours, but can be made 2 days in advance.
Run a paring knife around the edge of the pan, invert onto a serving plate that has a lip to catch the caramel.