Season the beef generously with salt and pepper. Heat 1 tablespoon of the olive oil in a large Dutch oven or heavy-based casserole over medium-high heat. Brown the beef in batches, taking care not to overcrowd the pan. Set aside.
Add another tablespoon of olive oil to the same pot. Lower the heat slightly, then sauté the onion for 5–6 minutes, or until soft and translucent. Stir in the garlic and cook for another minute. Add the tomato paste and cook, stirring, for 1–2 minutes.
Sprinkle over 2 tablespoons of flour and cook for 1 minute, stirring continuously. Slowly pour in the wine, stirring to deglaze the pan and scrape up any sticky bits. Add the stock, vinegar, bay leaves and bouquet garni.
Return the beef to the pot. Bring to a gentle simmer, then cover and place in a preheated oven at 160°C (fan-forced) for 2.5 hours, or until the beef is meltingly tender.
While the stew is cooking, heat the remaining olive oil in a frying pan. Fry the speck or pancetta until crisp, then remove and set aside. Add the mushrooms to the same pan and sauté until golden. Set aside.
Once the stew is nearly done, mix the extra tablespoon of flour with the softened butter to form a paste (beurre manié). Remove the pot from the oven and place on the stovetop over low heat. Stir in the mushrooms, pancetta and butter-flour paste. Simmer gently for 5–10 minutes to thicken. Taste and adjust seasoning.
Scatter with chopped parsley before serving.
Suggested sides: Creamy mashed potatoes, potato dauphinoise, or crusty bread with a simple green salad.