Heat a pan with 3 tbsp rapeseed oil to a high heat. Add 2 chopped medium onions. Keep the temperature hot and brown the onions. Add another 2 tbsp rapeseed oil after 3 minutes. The onions should take around 10 minutes to brown.
Once the onions are brown, add 1 cinnamon stick, 3 cloves, 1 black cardamon and 2 bay leaves. Keep the temperature high, add 2 tbsp ginger paste and 1 tbsp garlic paste. Cook until you feel the ginger is starting to stick to the pan.
Add the 200g chopped tomatoes. Turn the heat down and add 100ml water. This should deglaze the pan and release extra flavour. Reduce for around 15 minutes until the sauce has a thick consistency. You can now use your masala base to make a whole host of curries.