Optional: saute the onions in a little oil for 2 to 3 minutes. Add the spices and mix to coat the onions. Cook for a further minute. You may need to add a little hot water or stock to deglaze the base (just 1 - 2 tbsp. should be enough) to prevent anything from sticking to the bottom. This will also create a curry paste that you can coat the potatoes in when they are added.

Add the potatoes and give them a good stir to coat them in the onions and spices/paste.

Add the tinned tomatoes, tomato puree and vegetable stock. Give everything a good stir to make sure nothing is stuck to the bottom.

Set off on chunky or smooth (I used chunky).