For 4 people
Rust
1 egg yolk, 1 tbsp. to c. Dijon mustard (optional), 1 clove of garlic, 30 cl of neutral oil,
1 C. to s. mixture of spices of your choice: cayenne pepper, paprika, etc., salt.
Fish soup
1 kg of various fish carcasses, 3 carrots, 1 onion, 1 stalk of celery, 2 tbsp. to c. salt, 1 tsp. to c. pepper, 3 tbsp. to s. spice mix of your choice, 3 tbsp. to s. tomato paste, 1 bouquet garni.
The preparation
In a bowl, mix the egg yolk, the peeled and crushed garlic clove and possibly the mustard. Pour in the oil in a very thin stream to make the mayonnaise rise. Add the spices and salt. Adjust seasoning. Reserve in a covered bowl.
Collect the fish carcasses (bones, tails, heads, except the eyes and gills). Peel and cut the carrots, onion and celery into pieces. Arrange the carcasses in a gratin dish, add the vegetables. Season with salt, pepper and spices. Spread the tomato paste on top. Grill in the oven at 220°C for 30 min. Add the bouquet garni and 2 to 3 liters of water to cover everything. Reduce the oven temperature to 180°C, cook for another 45 to 60 minutes. Add water if necessary during cooking.
Remove the dish from the oven and pass the mixture through a strainer, grinding and pressing the mixture as much as possible. To obtain a very smooth soup, pass the collected mixture through cheesecloth. Adjust seasoning if necessary. Heat the soup in a saucepan. Serve in individual bowls, with toasted rye bread and rouille.