Place flour and salt in large baggie. Place roast in bag and shake to coat well.
Pour oil in large dutch oven. Sear the roast on all sides. Drain most of the oil. Add the broth, wine, bay leaves, and garlic. Bring to a boil then reduce to a simmer and simmer over med to low heat covered for 2 hours
Add more water if needed during this time. Make sure the roast stays covered by fluid. Add the potatoes, carrots, celery, and onions. Simmer another hour to hour and a half until roast is fork tender. Remove the roast from pot. Remove the veggies with a slotted spoon and arrange around the pot roast. Discard the bay leaves. I also discard the celery it gets too stringy.
Mix cornstarch with milk. Heat the roast juices to boiling and add the cornstarch mixture. Cook until thickened. Stir in the sour cream. Serve over the roast, potatoes and veggies.