Cod in winter vegetables--a piece of polish christmas tradition

Ingredients

• 4 - 6 half pieces of cod fillet
• 1 medium onion
• 1 cup grated carrot
• 1 cup grated celery root
• 3 tbsp tomato paste
• 4 tbsp grape seed oil
• 1/4 tsp ground nutmeg
• 2 tbsp chopped parsley
• salt and pepper