1. Pour 385ml boiling water into a large bowl, then add the potato mix, stirring all the time. Leave to stand for 1 minute, then beat thoroughly.
2. Drain the salmon, then skin, bone and flake it. Add the salmon to the potato with the Thai seven-spice seasoning, salt and pepper. Divide the mixture into eight and shape into cakes with lightly floured hands.
3. Spread out the breadcrumbs on a plate. Dip the fish cakes into the beaten eggs, then coat them in the crumbs.
4. Pour enough oil into a frying pan to just cover the base. Heat gently, add the fish cakes and cook for 3-4 minutes on each side over a low heat until golden brown. (You may have to do this in batches). Keep the fish cakes warm.
5. Take the Thai herb mix, deseed and finely chop the chilli and finely chop the lemon grass. Whizz together with the mango slices in a food processor until smooth, then press through a fine sieve. Finely chop the coriander and add to the sauce. Cook the fresh vegetable stir-fry.
6. Serve the fish cakes, topped with the sauce, on a bed of stir-fried vegetables.