To make the ravioli, place the trout in a food processor and blend briefly, then add the egg yolk. Next add the cream, season to taste and then blend to a smooth consistency. Place in a bowl and stir in the crabmeat, chives and basil.
Lay out the wonton wrappers on a clean work surface. Brush one wrapper with a little of the egg wash. Place a generous spoonful of the crab mixture in the centre of the pastry. Fold over the corner to make a triangle and fold the edges again to seal. Blanch in a pan of boiling salted water for 2 minutes, then remove with a slotted spoon and quickly refresh in a bowl of iced water. Arrange on a tray and chill until needed. Add in the pak choi and remove after a few minutes.
Heat stock in a pan, add the lemongrass, galangal, kaffir leaves, lime juice, fish sauce, chilli, coconut milk, tomato puree, palm sugar and sweet chilli sauce. Bring to the boil and let it simmer for a few minutes. Strain into another pot using a sieve.