In a food processor puree the onion, garlic, lemongrass, pineapple and ginger with about 50ml of vegetable oil and mix into a paste. Place in a hot pan and sweat off, mix all the spices with a little water and then add to the other mix. Cook for about 30 minutes until the mix is fragrant and looks like it has separated. Add the stock from the mussels and reduce by 1/2, then add coconut milk and again reduce to sauce consistency. Correct the seasoning and keep warm.
For the mussels add them to a large hot pan, add a splash of wine and cover with a lid. This will only take a few minutes, strain them off and remember to keep the stock for the curry sauce. Allow all to cool and remove the meat from the shells. Do not use any mussels that have not opened.
Peel and dice the sweet potato, place in a hot pan with a little olive oil and sweat off until soft, adding a spoon of curry sauce. Place the fish in a bamboo steamer and cook for 6/8 minutes. After about 6 minutes in place add the asparagus tips. Remove the cooked fish and leave the asparagus until soft.
To Serve: finish the dish reheat the curry sauce, add the mussels and a handful of the chopped fresh coriander. Place the sweet potato mix in the centre of the plate, place the fish on top, spoon some curry sauce and mussels around and garnish with the asparagus.