Monkfish in sweet and sour sauce

Ingredients:

• 900 g monkfish tail, cut into 2.5 cm pieces.
• 2 bay leaves
• Half a stalk of celery + 6 stalks of celery, cut into 2.5 cm pieces.
• Half a small onion, cut into pieces, + 3 medium onions, cut into rings
• 1/4 cup vegetable oil for frying vegetables
• 2 medium sweet green peppers, seeded and cut into 2.5cm pieces.
• 2 medium sweet red peppers, seeded and cut into 2.5cm pieces.
• One can (180 g) of tomato paste
• 1.5 cups apple cider vinegar
• 2 tablespoons of sugar
• 1.5 cups pitted green Italian olives, cut into pieces
• 4 tbsp of water

Preparation:

1. Season the monkfish pieces with salt. Bring a medium or large saucepan of water to a boil, add the bay leaf, half a celery stalk, and half an onion, and cook for 5 minutes.
2. Add the fish and cook for another 10 minutes. Drain and transfer the monkfish to a large bowl; set aside. Discard the celery, onion, and bay leaf.
3. In a large skillet, fry the celery pieces in vegetable oil until soft; add to the fish. Fry the red and green pepper pieces; add to the fish.
4. Sauté 3 chopped onions for about 5 minutes; add tomato paste, then vinegar. Mix well, add sugar and olive pieces, and cook for another 10 minutes, stirring frequently. Season with salt and pepper to taste.
5. Add the vegetable mixture to the fish and refrigerate. It's best served chilled.