Combine the first 5 ingredients in a large bowl. Remove the tail from shrimp, cut in half lengthwise and set them in the bowl. Add the mango, tomato, green onion, mint, coconut and salt and toss to combine. Refrigerate until ready to serve; can be made an hour before needed.
To serve, let diners fill lettuce leaves with the shrimp mixture, drizzle with sriracha and enjoy.
Note: Cooked, peeled shrimp or prawns are sold in our Seafood Department, thawed or frozen. If you bought the latter, thaw and pat dry before using.