Preheat the oven to 170C/340F/Gas 3. In a large bowl, mix the jerk seasoning paste with the olive oil and add the fish steaks and prawns. Cover and leave to marinate in the fridge for at least two hours. Meanwhile, make the sauce.
For the sauce, gently fry the onion, garlic, chilli and ginger in a large pan until softened; then add the remaining sauce ingredients. Bring to the boil and simmer for 30-35 minutes, or until the tomatoes are soft and the sauce has started to thicken. Remove from the heat and allow to cool.
Pour the sauce into a food processor and blend until smooth. Pass into a clean pan through a sieve, then simmer for a further 10 minutes, or until the sauce has thickened.
For the dumplings, line a baking sheet with greaseproof paper and scatter the sweet potato pieces over. Roast for 25-30 minutes, or until tender. Allow to cool then purée in a food processor or blender.
Mix together the flour, herbs and puréed sweet potato in a bowl.
Tip the mixture out onto a floured surface and knead, until you have a smooth dough. Roll the dough into sausage shapes about 1cm/½in thick then cut into 2.5cm/1in lengths.
Remove the prawns and fish from the marinade. Add the prawns, fish, cooked crab claws and clams to the sauce. Simmer for 5-7 minutes, taking care not to overcook the fish.
Just before the end of cooking, add the dumplings to the stew and cook for 1-2 minutes, or until they rise to the surface.
Serve at once in bowls.
