For the fish curry, place the cashew nuts, spices and chilli into a food processor and blend until smooth. Transfer to a shallow dish and reserve a tablespoon of the mixture for the spinach salad.
Coat the fish in the beaten egg, then roll in the spice mix. Heat the vegetable oil in a frying pan and fry the fish for 5-6 minutes, or until golden-brown all over and cooked through.
For the spinach salad, mix the reserved spice mixture with the lemon juice. Place the baby spinach and coriander into a bowl and pour over the lemon and spice mixture, then toss well to combine.
For the sweet potatoes, place the sweet potato slices into a saucepan with the oil, lemon juice and curry powder, and enough boiling water to cover. Simmer gently with a lid on for 7-8 minutes, or until the sweet potato is tender.
To serve, spoon the sweet potato slices onto a serving plate and arrange the spinach salad alongside. Spoon the fish curry on top of the sweet potato slices.