Toss The Meat with the flour and set aside. Heat the oil in a skillet over high heat until nearly smoking. Add the meat in batches and without crowding, brown well on all sides. Remove pieces as they are done and reserve on a plate. Discard the cooking fat and reduce heat to low. Add onion, celery, turnip and carrot. Cover and cook for 10 minutes. Add the garlic and wine, raise the heat and cook, uncovered, until the wine has reduced to almost nothing. Add the stock and continue to cook until reduced by about 2/3. Add the peas to the skillet and replace the meat and any juices that have collected on the plate. Add the salt and sage. Place in refrigerator to chill for 30 minutes. Preheat the oven to 375F. Line a 9-inch pie dish with your pastry and pour in the meat, vegetable and sauce. Cover the top of the pie with the rest of your pastry. Poke a few holes in the top to allow steam to escape during baking. Brush lightly with egg. Place in oven and bake for 30 minutes. Serve immediately.