Place the meat in a large, resealable plastic bag or a container with a tight-fitting lid. Pour in the wine, making sure that each piece of meat is submerged in the wine. Let the meat marinate in the refrigerator for at least four hours or overnight.

Place one tablespoon of oil at the bottom of the slow cooker. Add potatoes, leeks, carrots, garlic and celery to the slow cooker.

Combine the rosemary, thyme and flour in a large shallow plate. Pour the meat into a colander set over a large bowl and set aside the wine. Dry the meat on paper towels and generously season each piece with salt and pepper. Dredge the meat in the flour mixture and shake each piece to remove any excess flour.

Heat a large sauté pan over medium heat and lightly coat the pan with olive oil. Brown the meat on all sides, in batches if necessary, for about six minutes. Transfer the meat to the slow cooker. Add about one cup reserved wine to the slow cooker with the tomato paste and stir gently. Stir in chicken stock and season with salt and pepper.

Cook the stew for two hours on high and then five hours or more on low, until the meat is tender (the meat should be pierced easily).