Set a saucepan with 1 tbsp vegetable oil over a medium heat. Add the onion and fry for 3-5 minutes, until soft and translucent. Stir in the curry paste and tomatoes and cook for 6-8 minutes more, until the tomatoes are soft and starting to break down.
Pour in the coconut milk, cover with a lid and simmer for 20-25 minutes, stirring occasionally, until the sauce has thickened. Stir the shredded lamb into the sauce and warm through for 2-3 minutes.
Meanwhile, cook the rice according to pack instructions.
Set a small frying pan with the remaining vegetable oil over a medium-high heat. Toast the cumin seeds for 30-60 seconds until fragrant. Stir into the rice and add the coriander.
Divide the rice between two warm bowls, top with the lamb curry and serve parathas on the side, if you like.