Peel and finely chop the onion. Halve the pepper. Scoop out the seeds and white bits and finely chop it. Peel the sweet potato and finely chop it. Peel and grate or crush the garlic. Finely chop the parsley stalks (keep the leaves for later).
Warm a pan over a low heat. Add 1 tsp oil and the onion, pepper and sweet potato. Season well. Cook and stir for 5 mins till the onion looks soft and glossy. Add a splash of water if the veg start to stick.
Add the garlic and parsley stalks to the pan. Measure out 1 tsp each of the cayenne, fennel and coriander seeds and stir them in. Cook and stir for 1 min till the pan smells aromatic.
Tip the tomatoes into the pan. Drain the chickpeas and add them to the pan. Cover. Simmer for 10 mins till the sauce thickens. Stir now and then.
While the chickpeas cook, heat your grill to high. Line a baking tray with baking paper. Season the hake with salt and pepper. Lay on the baking paper, skin-side down. Grill for 8-10 mins till the fish is opaque, white and flakes easily when you press it with a fork.
Taste the chickpeas and adjust the seasoning if it needs it. Spoon the chickpeas into two warm bowls. Top with the hake fillets. Garnish with the roughly chopped parsley leaves.