I had Key West Grill's Coconut Mango Dressing when I lived in the area 12 yrs. ago. I asked the kitchen for the recipe and they wrote down the ingredients for me as follows:

Mayonnaise
Sour Cream
Coco Lopez (comes in a can,like evaporated milk)
Mango Chutney
Lime Juice

I've experimented with these ingredients and my version seemed to be very close to what I had there at the time. I don't know about 12 yrs. later, their recipe may have changed.

Coco Lopez is found in supermarkets in the Spanish Food section and/or with the mixers for alcoholic drinks. I have also used orange marmilade in place of the mango chutney and it's good that way too. Hope this helps.