Preheat the oven to 450°. Cook the garlic in boiling water for 10 minutes, then drain. In an 8-by-11-inch roasting pan, season the chicken legs with salt and pepper and scatter the garlic, thyme, lemon slices and bay leaf around them. Whisk the stock, then the wine into the flour and pour over the chicken. Cover tightly with foil, bring to a boil on the stove, then braise in the oven for 20 minutes. Reduce the oven temperature to 350°, remove the foil and turn the legs. Braise for about 1 hour and 10 minutes longer, or until tender.