There are many versions of this dish, which, here, is built in layers.
In small mixing bowl beat together garlic, oil, wine, pepper, and cumin. Line a large, oven-proof casserole with a layer of onions. Add a layer of fish, a layer of squid, sprinkle with some parsley, add a layer of potatoes, a layer of tomatoes, and a layer of peppers. Sprinkle with half the garlic and oil mixture. Repeat layers, ending with onions. Sprinkle with remaining garlic and oil. Cover and simmer 30 minutes. Season with salt. Garnish with chopped parsley.