How to Make It
In a large skillet, heat the olive oil. Add the shallots, carrot and prosciutto, cover and cook over low heat, stirring once or twice, until the shallots are softened but not browned, about 6 minutes.
Blanch the cherry tomatoes in boiling water just until the skins loosen, about 10 seconds. Drain in a colander and rinse under cold running water. Peel the tomatoes and cut them in half crosswise. Scoop out the seeds and pat the tomatoes dry.
Rub the sage all over the roast and season with pepper. Push the vegetable mixture to the side of the skillet. Add the beef. Cook over high heat until well-browned all over, about 12 minutes. Season the beef with salt and stir in the mushrooms and chopped tomatoes. Add 3/4 cup of the wine and boil for 3 minutes. Add the stock and bring to a simmer. Cover and simmer gently over low heat, turning the meat once or twice, about 25 minutes for rare. Transfer the roast to a carving board and cover loosely with foil.
Add the remaining 1/2 cup of wine to the skillet and boil over high heat for 5 minutes. Transfer the mixture to a food processor and puree until smooth. Return the puree to the skillet and bring to a simmer over moderate heat. Add the cherry tomatoes, season with salt and pepper and cook for 2 minutes. Remove from the heat and swirl in the butter.
Thinly slice the meat and arrange on 8 dinner plates. Spoon some of the sauce and cherry tomatoes over the meat and serve at once. Pass any remaining sauce separately.