For the rough puff pastry, sift the flour and salt into a mixing bowl. Incorporate the butter and briefly rub it in to the flour, but with chunks of butter remaining.
Add the egg yolks, pour in most of the water and mix together to form a firm dough. Add a little more water if necessary. Roll the pastry into a ball, wrap in cling film and chill in the fridge for 20 minutes. Set aside the egg whites for glazing the pastry.
Take the dough out of fridge and roll out on a floured surface to a rectangle 20x60cm/8x24in. Then fold the bottom third of the rectangle into the middle and the top third over the top (like folding a letter).
Rotate the pastry 90 degrees and roll out and fold again as before. Repeat the rolling and folding once more and wrap in cling film. Set aside to chill in the fridge.
For the lentils, bring the stock to the boil in a small saucepan and add in all the ingredients for the lentils. Reduce the heat and simmer 30 minutes until the lentils have cooked and the liquid has evaporated.
Preheat the oven to 200C/400F/Gas 6. Line a baking tray with parchment.
For the sea bass, combine the fish sauce, curry powder, lemongrass, ginger, chilli, garlic and salt and pepper in a bowl. Add the fish and mix until well coated. Set aside to marinade while you make the pancakes.
For the herb pancakes, whisk together all the pancake ingredients, except the oil, to form a batter.
Heat a 25cm/10in frying pan over medium heat, add a tablespoon of olive oil and ladle in half the batter, tilting the pan around so that the batter completely covers the pan base. Fry for one minute on each side and transfer to a plate. Repeat with the remaining mixture set aside (you will only need one pancake).
Take the pastry from the fridge. On a lightly floured surface, roll out 400g of the dough in to a rectangle about 50x15cm/20x6in and place onto the lined baking tray.
Lay one pancake on top of the pastry. Pat the sea bass dry of marinade with kitchen towel, then lay one fillet on top of the pancake, followed by the lentils. Top with the second sea bass fillet.
Roll out the second piece of pastry to a rectangle roughly 60x20cm/24x8in.
Wrap the pancake up around the sea bass and brush the surrounding pastry edge with the reserved egg white. Place the second rectangle of pastry on top and press down to seal. Cut the pastry into the shape of a fish, ensuring that the pastry is still sealed around all the edges. Brush the whole fish with egg white, then score the pastry with fins and scales. Flick your knife in at an angle making sure not to completely pierce the pastry.