Preheat the oven to to 200°C, fan 180°C, gas mark 6.
Heat 1 tablespoon of the olive oil in a deep frying pan. Add the onion and the coriander, reserving a little to garnish. Sauté for a couple of minutes until starting to soften.
Stir through the Thai red curry paste and add the dried red lentils and 500ml cold water. Simmer for 5 minutes and stir in the chopped tomatoes, then simmer for a further 10 minutes, or until the lentils are tender.
Meanwhile, brush the pittas with olive oil and sprinkle with a pinch of curry powder, then place on a baking tray and bake in the preheated oven for 5 minutes.
Just before serving, sprinkle chopped coriander into the curry and serve with the hot pittas.