Rinse the fish fillets and pat them dry with paper towels. Season with salt, pepper, and lemon juice. Set aside.
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, ground paprika, ground cumin, ground coriander, and ground turmeric. Cook for about 5 minutes, until the tomatoes are soft and the spices are fragrant.
Add the chopped pumpkin and okra to the pot. Stir well to combine with the tomato mixture. Pour in the fish broth or water and bring to a boil. Reduce the heat and let it simmer for about 15 minutes, or until the pumpkin is tender.
Stir in the chopped spinach or collard greens and the peanut butter. Mix well to combine. Continue to cook for another 10 minutes, until the greens are wilted and the peanut butter is well incorporated.
Gently place the seasoned fish fillets into the pot. Simmer for about 10-15 minutes, or until the fish is cooked through and flakes easily with a fork.
Taste the stew and adjust the seasoning with salt and pepper if needed. Serve the muamba de peixe hot with rice, funge, or bread.
Enjoy your meal!