Method
Halve the cucumber and reserve half for another use. If using regular waxed cucumbers, scrub the skin to remove wax and remove seeds before dicing.
With a vegetable peeler, remove 4 lengthwise strips of skin and discard. Cut the cucumber in half lengthwise and then into 1/8" dice.
In a medium bowl, whisk together the mango purée, ginger, garlic, salt, rum, orange zest, orange juice, thyme and vegetable oil; stir in the cucumber.
Taste the vinaigrette for seasoning and chill until needed.