Place the shrimps in a bowl. Sprinkle with salt and pepper. Pour in the kalamansi and pineapple juices. Toss. Set aside.
Roughly chop the onion.
Mince the garlic.
Heat the butter in a frying pan.
Add the chopped onion, minced garlic and thyme. Saute until fragrant.
Drain the shrimps and add to the pan. Cook for about 30 seconds per side.
Add the marinade, mango cubes and pineapple tidbits.
Season with fish sauce, rice vinegar and sugar.
Allow everything to cook for a minute or two to allow the flavors to blend.
Serve the shrimps with sweet mangoes and pineapple immediately.
Serving suggestion: Place rice on bowls. Top with the shrimps with sweet mangoes and pineapple. Drizzle in some of the pan juices. Sprinkle with parsley.