In a shallow dish, combine the flour, thyme, ginger, and savory. Dredge the meat with 2 tablespoons of this mixture, shaking off any excess. Heat the oil and butter in a Dutch oven and brown the meat thoroughly. Remove the meat from the pan. Brown the onion until quite dark and crisp, but do not allow to burn. Remove from the pan. Pour the wine or water into the pan juices to deglaze the pan, then add the stock and bay leaves. Add salt and pepper to taste. Put the meat and onion back in the pan and simmer, covered, for 1-½ to 2 hours, or until the meat is tender.
About 30 minutes before the meat is done, add the carrots, pearl onions, and potatoes. Add the peas during the last few minutes of cooking. Dissolve the remaining 2 tablespoons of the flour mixture in a little cold stock or water. Use it to thicken the gravy. Gradually whisk the sour cream into the thickened gravy, being careful not to allow it to boil.