Start by making the sauce. Finely hop the chilli, keeping the seeds in. Then finely chop the garlic. If you have a mortar and pestle, pound them, otherwise keep chopping as finely as you can with a knife.
Transfer to a small dish along with all the other sauce ingredients, but keep some of the chilli aside. You can add more later once you have tasted. Mix well and taste. If it is too spicy for your taste add more sugar, water or lime juice. If you want it spicier, add the remaining chilli.
If your mackerel isn’t filleted already, fillet it. This is an easy fish to fillet because the bones are large and firm. Season the fillets on both sides. Heat a little olive oil in a pan and fry your fillets til they are gently browned on both sides, about 3-4 mins on each side, skin side first. When cooked, transfer to a small plate. It’s up to you whether you leave the fillets whole and let your guests break pieces off, or cut them into small pieces yourself.
If your rice noodles are dried, cook according to packet instructions. If they are fresh, remove from the packet and separate any that have stuck together. Set aside. The noodles should be no warmer than lukewarm – you don’t want them burning your fingers or wilting the leaves.
When your fish is done, lay out all the components on a large plate or board. Give each guest a small plate and let them make their own wraps, starting with a lettuce leaf, then a small pile of noodles, then a piece of fish, a coriander sprig, a couple of mint leaves and finishing off with a drizzle of the sauce.