Put the lime zest into a bowl with the shrimp. Squeeze over the juice of 2 of the limes and add the fish sauce. Mix well and leave to marinate for about 10 minutes.
In a pestle and mortar or a food processor, pound or blitz the chillies, garlic, ginger, cilantro stalks, sesame oil and lime leaves until you have a paste.
Heat up a wok and add a few tablespoons of olive oil and add the paste, stirring quickly. Cook for about a minute before adding the shrimp and all of the juices from the bowl. Cook for another minute, stirring. Then add the tamarind paste, coconut milk and chicken stock. Turn the heat down and simmer slowly for about 15 minutes. Taste - you may need to add more salt and pepper or more fish sauce, and just enough lime juice to give it a good pop!
Get a pot of water boiling for the noodles or rice.
Lightly score the scallops with a criss-cross pattern on one side so that when they cook they will open out to look like flowers, then lightly season with salt and pepper. Get a large non-stick frying pan hot and pour in a little olive oil. Put the scallops into the pan and cook a couple of minutes on each side until golden.
Halfway through, add the noodles or rice to the boiling water and cook according to the packet instructions.
Remove the scallops from the heat. Drain the noodles or rice and divide between four serving bowls, spooning the laksa stew over the top. Sprinkle with cilantro leaves. Then lay two or three scallops on top of each bowl.