Spray 10 squirts of oil into the cooker and put over a medium heat.
Add the onions, soften by stirring for a couple of minutes, then mix in the spices, garlic, chilli & pepper and continue stirring for 2 more minutes.
Pour in the stock, loosen any pieces stuck to the pan then add the black beans & sweet potatoes.
Turn up the heat, put on the lid and bring up to pressure for 10 minutes. Remove from flame and allow the cooker to cool by itself.
Remove the lid when depressurised. Add the tinned tomatoes and purée, stir well and cook over a medium heat for a further 5 minutes.
Season to taste, then serve with rice and garnished with coriander.