Peel and dice onion and garlic. Rinse peppers, quarter, remove seeds and cut into strips. Blanch the tomatoes, peel, remove the stalks and cut into small cubes.
Remove seeds from chili and cut into small strips. Remove peel from potatoes, rinse and cut into cubes. Cut tuna into 2-centimeter cubes.
Marinate tuna cubes with juice of lemon, salt and pepper in a baking dish for about 30 minutes. In a large frying pan, heat the olive oil and sauté the onion cubes until translucent, then add the garlic and bell pepper strips and sauté at a low temperature for about 5 minutes until soft. Add salt, tomatoes, chili, pepper and paprika powder and cook on low heat for 10 minutes. Cover the pan with the potato cubes and the wine.
Finally, add the tuna cubes and cook for 5 minutes.