Place the dried porcinis in a small saucepan with the red wine, and bring to a low simmer. Steep the mushrooms in the wine for 5 minutes before straining the wine to trap any grit that may have come off the mushrooms. Rinse the mushrooms under running water, and pat dry. Use a knife to roughly chop the mushrooms, and set them and the wine aside until needed.
Season the turkey with the salt and pepper and coat evenly with the flour. Place a wide-mouthed, straight-sided saute pan over medium heat. Add the 1/4 cup olive oil to the pan and once hot, sear the turkey in the pan until golden brown on all sides, about 8 minutes per side. Remove the turkey from the pan, and pour off the fat from the pan. Use a paper towel to wipe the pan and return it to the stove. Add the remaining 2 tablespoons of olive oil to the pan. Once the oil is hot, add the onions, carrots, celery and tomato paste to the pan and saute, stirring occasionally, until the mirepoix and tomato paste are slightly caramelized, about 5 minutes. Add the garlic to the pan and saute until fragrant, about 30 seconds.
Deglaze the pan with the red wine. While the wine is reducing, add the mushrooms to the pan and continue to reduce the wine until it is nearly completely evaporated. Stir the stock into the pan and add the bay leaves and thyme. Bring the stock to a boil and return the turkey to the pan. When the stock returns to a boil, reduce the heat to a simmer and cook the turkey, covered, until the meat is fork tender, about 2 1/2 hours, turning the turkey midway to ensure even cooking.
When the turkey legs are tender, taste the sauce and re-season it if necessary. Serve the turkey while hot on a bed of polenta with the sauce.