1. Place the chilli, lemongrass, ginger, garlic, salad onions and coriander in a food processor and blitz, scraping down the sides of the bowl using a spatula in between each process until you have a coarse paste.
2. Heat the groundnut oil in a non-stick frying pan and season the salmon with a little sea salt. Cook the salmon fillets for about 1-2 minutes each side over a high heat until cooked through and beginning to brown. Set aside.
3. Add the chilli and coriander paste to the frying pan and cook for 2-3 minutes, then tip in the tomatoes, rinsing out the can with half a can of water and adding this to the sauce. Stir in the coconut milk, fish sauce, lime juice and green beans and cook for 7-8 minutes, stirring regularly until the sauce is reduced and thickened, and the beans are tender.
4. Cut the fish into large pieces and return to the pan to cook for a further 1-2 minutes. Serve with jasmine rice and extra coriander on the side, to taste.