In a large heavy pot or Dutch oven, cook the onions and carrots in the oil on medium heat until soft, about 8 minutes.
Add the bacon and continue cooking and stirring for 8 minutes.
Add the meat and cook, turning several times, until browned on all sides. Sprinkle the meat with salt and pepper. Add the herbs, the garlic and the red wine. Cover, turn down the heat, and let simmer for at least two hours.
Meanwhile cook the mushrooms in the butter until soft and add to the stew after about two hours along with the tomato concentrate.
Simmer until meat is very tender. Sometimes I cook it for the last hour without the lid to get a more concentrated sauce.
If you are thickening your stew before serving, mix the butter and flour together in a small bowl until well blended. Blend in a tablespoon of the cooking liquid, and then stir this mixture back into the stew. Continue cooking for several minutes.