2) Place the lemongrass, all but 2 tbsp of the coriander, 1/2 the mint, 8 tbsp of the oil, the garlic, jalapenos, paprika and salt in a food processor or blender and process until smooth. Add the remaining 8 tbsp of oil and vinegar and process until smooth. Place the fish fillets in a large baking dish, cover with the mojo and turn to coat. Marinate fish for up to 1 hour.
3) Place four (40cm) long pieces of greaseproof paper on your work surface with the short half facing you. Crease each down the middle. Place a fillet in the centre of the bottom half of the rectangle, pour about 60ml of the mojo over each fillet and sprinkle with the remaining 2 tbsp of coriander. Fold the top half of over the fillet so that the top and bottom edges meet.
4) Tightly crimp and fold the edges of the greaseproof paper working from one end around to the other to seal the package. Place the packets on a baking sheet and bake for 9 to 10 minutes for 2cm-thick fillets or up to 12 minutes for 2.5cm-thick fillets.
5) Place the fish packets on a large serving dish and open the packets tableside. Serve with juices from the packet and sprinkled with the chopped coriander and mint leaves.