Combine the sugar, fish sauce and tamarind juice in a pan and dissolve the sugar by warming gently. Reduce this liquid by half and add the lime zest. Heat the peanut oil in a frying pan and add the shallots and sweat off, then add the garlic, followed by the chilli. Add the langoustine and cook off quickly. Add the reduced tamarind liquid and cook the prawns in the liquid, taking care not to overcook the prawns/langoustines, taste and adjust the seasoning with the lime juice. For the maple leeks, shred the washed leeks very fine. Heat a heavy based pan with the unsalted butter then add the leeks, sweat off. Add the maple syrup and coat the leeks. Add the vegetable stock and star anise and cook down gently until, all the liquid has reduced and coated the leeks. Disregard the star anise. Serve the leeks onto a warm plate and top with a lightly poached egg.