Preheat your oven to 190°C/375°F/gas mark 5.
Cook the potato chunks in a pan of salted boiling water for about 10 minutes until soft. Then drain and mash with a glug of olive oil, the turmeric and a pinch each of salt and pepper.
Pan-fry the onion, carrot and courgette in a splash of olive oil over a medium heat for about 5 minutes until the onions have softened a bit. Add the curry powder, season and continue to fry for a further minute before adding the chopped tomatoes. Simmer for about 5 minutes. Season to taste, then transfer to a round ovenproof dish and top with the mash. Bake for about 25 minutes until the mash starts to colour, then serve.