Heat the vegetable oil over a medium heat, then add the onion, garlic, ginger, chilli and spices and cook for 3 minutes. Add the chicken and chopped tomatoes and 100ml water. Bring to the boil, then reduce to a simmer, cover the pan with a lid and cook for 10 minutes. Remove the lid and cook for a further 5 minutes. Season to taste.
Meanwhile, heat 1 tbsp oil in a large, non-stick frying pan and fry the paneer over a medium-low heat on all sides until golden. Remove and set aside. Add the remaining oil to the pan, then the spinach. Cook until just wilted, remove to a chopping board and leave to cool slightly, then chop.
Add the onion and garlic to the pan and cook for 7 minutes until soft and golden. Add the paneer and chopped spinach back to the pan, along with the garam masala. Heat for 1 minute, then set aside.
Combine the yogurt and cucumber in a small bowl with a pinch of salt and pepper. Serve the curry with the saag paneer and raita.