Heat the olive oil in a large saucepan or casserole over a medium heat.
Add the onion and cook gently for about 5 minutes until softened.
Stir in the garlic, cumin seeds, coriander seeds and paprika, and cook for 1 minute until fragrant.
Add the red pepper, carrot and cauliflower, followed by the tomato purée. Stir well so the vegetables are coated in the spices.
Pour in the chopped tomatoes and season with salt and pepper.
Add the red lentils and, if needed, a little water or vegetable stock until the vegetables are just covered.
Bring to the boil, then reduce the heat, cover and simmer for about 20 minutes, or until the lentils and cauliflower are tender.
Stir in the chopped kale and cook for another 5 minutes until it has wilted.
Add the prawns. If using raw prawns, cover and cook for 3–5 minutes until they turn pink and are cooked through. If using cooked prawns, simply stir them in and warm through for 1–2 minutes.
Taste and adjust the seasoning before serving.