In a bowl, toss the fish fillets and shrimp with the lemon juice, ground black pepper, and a pinch of salt. Set aside to marinate for about 15 minutes.
In a large pot, heat the red palm oil or vegetable oil over medium heat. Add the finely chopped onion and sauté until soft and translucent. Add the minced garlic and cook for another minute.
Stir in the chopped tomatoes and tomato paste. Cook for about 5 minutes, until the tomatoes soften and the mixture becomes fragrant.
Add the chopped spinach or collard greens and sliced okra to the pot. Stir well to combine with the tomato mixture. Cook for about 10 minutes, until the greens are wilted and the okra is tender.
Gently add the marinated fish fillets and shrimp to the pot. Pour in the water or fish stock. If using dried shrimp, add them now as well.
Stir in the ground peanuts and ground paprika. Season with salt to taste.
Bring the mixture to a gentle boil, then reduce the heat and let it simmer for about 20-25 minutes, or until the fish and shrimp are cooked through and the flavors are well combined.
Ladle the calulu into bowls and serve hot. It can be enjoyed on its own or with a side of rice, funge (a type of Angolan porridge made from cassava flour), or bread.
Enjoy your meal!