How to Make It
Preheat the oven to 375°. Season the lamb all over with salt and pepper. Heat the oil in a very large skillet. Add the lamb and cook over moderately high heat, turning once, until browned, about 12 minutes. Transfer the lamb to a roasting pan.
Add the carrots, celery, onions and garlic to the skillet and cook over moderate heat, stirring occasionally, until just softened, about 10 minutes. Add 1 cup of the wine and boil until nearly evaporated, scraping up the browned bits from the bottom of the skillet. Scrape the mixture into the roasting pan.
Roast the lamb for about 40 minutes, until an instant-read thermometer inserted in the thickest part of the meat registers 125°.
Meanwhile, cover the morels with hot water and let soak until softened, about 30 minutes. Remove the morels from the water and pat dry, then thickly slice them.
Transfer the lamb to a carving board. Set the roasting pan over moderately high heat. Stir in the tomato paste and cook until beginning to brown, about 4 minutes. Add the remaining 1 cup of wine and bring to a boil, then stir in the chicken stock. Strain the liquid into a large saucepan and boil over moderately high heat until the sauce is reduced to 2 1/2 cups, about 20 minutes. Season with salt and pepper.
In a medium skillet, melt the butter. Add the sliced morels and minced shallot, season with salt and pepper and cook over moderately high heat until the shallot is softened, about 5 minutes. Add the sauce and bring to a boil. Stir in the parsley and season the sauce with salt and pepper. Thinly slice the lamb and serve with the sauce and the Sheep's-Milk Ricotta Gnocchi.