Prepare Sweet Potatoes: Trim the ends of the sweet potatoes, cut them into large pieces, and boil in salted water until tender, about 15-22 minutes. Drain and let cool, then peel and cut into smaller, bite-sized pieces.
Prepare Salted Cod: Prepare the salted cod by either boiling it to remove most of the salt or soaking it overnight, then flake it, removing any bones.
Fry the Dish: In a medium flame, heat olive oil in a pan. Add butter, diced onion, prepared salted cod, thyme, garlic, black pepper, and scallion. Cook for 3-4 minutes until fragrant. Add the sweet potato pieces and toss to coat in the mixture. Let heat through for another 2 minutes.
Serve: Serve hot as a comforting one-pot dish or as a side. Optional: Add smoked paprika for a smoky, sweet heat flavor.