First you need to make a flavor base for the tagine: Cut a cross over the bottom nodule of the tomatoes and blanch in boiling water. Then peel skin away, cut into quarters, and seed.
Burn the outside of the pepper over a naked gas flame. When the skin is black, place pepper into plastic bag and seal. When cool enough to handle, rub from the outside to remove all the pepper skin, split, and seed.
Pour 1 tablespoon of olive oil into a casserole dish, or tagine. Chop the pepper and tomatoes and place in the dish, add the chopped onion and some garlic. Heat over a flame to cook slowly.
Then start making the marinade for the fish: Crush the fresh cilantro and flat leaf parsley with a pinch of salt in a pestle and mortar. Place into a flat mixing bowl with 1 tablespoon of olive oil. Add turmeric, ground ginger, and black pepper.
Prepare the fish by chopping the heads and tails off, slice diagonally across its body to allow the flavors to penetrate the fish. Add sea bass, red mullet, and squid to marinade. Leave for 10 to 15 minutes.
Add the fish to the flavor base, big pieces first. Leave the squid for last minutes, as this does not take long to cook. Cook over the heat for 10 minutes. Then add the squid and shrimps and any leftover juices. Cook for a further 5 minutes.