Place beef in a bowl with 2 teaspoons of the oil and toss to coat. Heat a large flameproof casserole dish over a high heat. Add the beef, in batches, cook for 2 minutes or until browned. Remove and set aside.
Return pan to a medium-high heat, add remaining oil and onion, cook stirring occasionally for 3 minutes or until golden. Add the curry paste, cook stirring for a further 1-2 minutes or until fragrant. Add the tomatoes and 375ml (1½ cups) water, bring to the boil.
Cover dish and transfer to preheated oven for 1 hour. Add pumpkin and cashew nuts to pan, return to oven for a further 30 minutes or until beef is very tender. Stir through the spinach, yoghurt, lime juice and sugar.
Serve curry with steamed rice, garnished with coriander.
This curry is suitable to freeze, place in airtight containers, set aside to cool, then cover and freeze.
This curry can also be cooked on the stovetop. At the end of step 2, reduce heat to low, cover and simmer gently for 1 ½ hours. Add pumpkin and cashews, remove lid and simmer for a further 45 minutes or until beef is very tender and sauce has thickened. Stir through spinach, yoghurt, lime and sugar.