Wash the rice and place into a rice cooker with 2-1/2 cups of water and a pinch of salt and set aside to cook away.
Place the shallots into a deep sauté pan with the oil and some salt.
Place the pan over a medium heat and cook for five minutes until the shallots are softened.
Whilst the onion cooks, bash the coriander, garlic and zest of the limes in a pestle and mortar until a rough paste forms. Stir the coriander-garlic paste along with the green curry paste into the pot with the shallots.
Cook everything for a few minutes to release the flavours.
Add two tablespoons of the coconut milk from the top of the tin to the pan and cook, stirring, for a couple of minutes until the coconut starts to release its oils.
Pour in the rest of the tin alongside the stock and bring to a simmer.
Add the lemongrass to the pan and stir.
Stir the green beans and spring onions into the pan as well.
Add the white fish and prawns then season with the sugar, fish sauce, and lime juice and leave everything to simmer away for 3 - 4 minutes until the fish & prawns are cooked and the green beans are tender.
Remove the lemongrass before serving.
Serve with the cooked rice and some lime wedges, plus extra herbs for garnishing.