In a heavy saucepan over high heat combine the sugar with 1/4 cup of water. Stir just to combine. Simmer until the mixture has reached a deep amber color. Pour immediately into a 9-inch cake pan, swirling to completely coat bottom. Set aside to cool and harden.
In a blender combine all the remaining ingredients except the lime zest and flaked coconut. Blend well. Add the lime zest and pulse a few times just to combine. Pour into the cake pan with the caramel. Bake in a water bath until set (the center will still be slightly wobbly), about 1 hour. Remove from the oven and let cool completely on the courter. Refrigerate for 2 hours.
Put the flaked coconut in a large dry skillet over medium-low heat. Let toast until the flakes become light brown, making sure to stir often. Remove from heat and let cool before garnishing the flan.
Run a knife around the edge of the flan. Invert it onto a large plate with room for the sauce to pool. Cut into slices, garnish each slice with a bit of the toasted coconut and serve.