Salt and pepper the lamb. Warm the olive oil in a wide-bottomed pot. When the oil is very hot, add the lamb. Brown the meat well on all sides over medium heat for 10 minutes. Remove it from the pan.
Add the carrot, celery, shallot, garlic and thyme and cook over low heat, loosening any brown pan crust with 2 tablespoons of water. Add the meat to the pan and stir in the flour. Cook over medium-low heat for 5-8 minutes.
Raise the heat to high, add the dry red wine and bring to a boil. Reduce the heat and simmer, covered, 2 hours. Remove the meat from the sauce, discard the thyme and puree the sauce in a food processor. Return the meat to the sauce, stir in the vinegar and serve. Can be made a day in advance and gently rewarmed.