For the broth
1. Remove the fillets from the sea bass. Set aside the fillets and wash the bones in a bowl.
2. Place the bones in a pot with all the ingredients for the broth. Simmer for about 30-35 minutes.

For the ragout
1. Cut the spinach and leek into small pieces. Also cut the celeriac into small cubes and boil in water until softened. Remove from the water and dry.
2. In a small pot add all the ingredients for the ragout. Add 2-3 tablespoons of olive oil, salt and pepper and cook for about 2-3 minutes.

For the sea bass
1. Carefully remove all small bones from the fillets. Sauté in a hot pan with some olive oil. Finish in the oven for about 3-4 minutes.

For the avgolemono 
1. In a saucepan add the yolks, lemon juice, cream, corn flour salt and pepper and mix with the fish broth. Remove from the heat and mount with butter. Pour the ragout in, stir and serve.