1. Zest 2 oranges and squeeze the juice of 1 orange with the lemon juice.

2. Marinate the meat in the refrigerator with the citrus juice.

3. Put the meat and marinade in a pot, generously cover with water, and bring to a boil. Let cook for 40 minutes, skimming regularly. Add the onion, bay leaves, leek, and carrots cut into chunks. Season with salt and pepper, cover, and let simmer for another hour.

4. Peel the sweet potatoes, cut into rounds, and plunge into boiling salted water for 10 minutes.

5. Preheat the oven to 180°C.

6. Drain the sweet potatoes and place them in a buttered dish with 50g of butter. Put in the oven.

7. After 10 minutes of cooking, drizzle with 2 tablespoons of water, cover with aluminum foil, and continue cooking for 10 minutes.

8. In a saucepan, melt 40g of butter, add the flour, and gradually incorporate the filtered meat broth. Add the zest and juice of the last orange. Mix over low heat to obtain a creamy sauce.

9. Remove from heat and incorporate, whisking, the egg yolk mixed with the cream and coriander. Incorporate the sauce into the pot with the cooked meat. Remove the sweet potatoes from the oven.

10. Serve the blanquette with the sweet potatoes.