Heat the vegetable oil in a large pot over medium heat. Add the onion and cook for 4 minutes until it softens.
Stir in the garlic and ginger and cook for 1 minute until fragrant.
Add the sweet potato cubes and stir to coat them with the oil and aromatics.
Spoon in the peanut butter, then pour in the coconut milk and vegetable broth. Stir until the peanut butter melts into the liquid.
Add the paprika, cayenne, salt, and black pepper. Bring the mixture to a gentle simmer and cook for 12 minutes until the sweet potatoes are tender.
Gently place the fish pieces into the broth. Simmer for 6 to 8 minutes until the fish flakes easily and is cooked through.
Ladle the stew into bowls and top with chopped cilantro. Serve with lime wedges on the side.