Firstly, lay the pastry on a buttered sheet of baking parchment and place it in the fridge.
Heat the sesame oil in a frying pan, whisk the eggs together, then add to the pan and cook to make a thin omelette. Put aside to cool (keep approx ¼ of an egg, to glaze the pastry).
Roughly chop the pak choi. Finely chop the coriander, lemongrass and chillies and mix with the grated garlic, ginger and lime zest.
Take the pastry out of the fridge. Trim the omelette so that it is roughly the size of the salmon.
Place the omelette in the middle of the pastry, then cover the omelette with the pak choi, followed by the salmon. If the salmon tail is thin, fold it over on top of itself so that the salmon is roughly an equal thickness. Sprinkle the spice mixture over the salmon and a little of the lime juice.
Fold the pastry over the salmon making a neat parcel. Where it joins, use the egg wash to glue it together. Trim the excess so that you don’t have lumps of pastry (as they will not cook). If you have excess pastry you can cut-out some shapes and decorate the top before using the egg wash to glaze the pastry.
Place on a preheated baking sheet, in a preheated oven at 180°C for 30 minutes, or until the pastry is crisp and golden.
Serve hot with new potatoes.