Saute onion & garlic with oil in the cooking pot till transparent. Season the roast with salt & pepper and then dredge (lightly) in flour. Brown roast (on top of the onions & garlic) in the crockpot on both sides (10 min). Transfer to the slow cooker, add the stewed tomatoes, water and worcestershire sauce. Cook on setting 4 (of 5) for about 5 hrs. When done, puree the remaining tomatoes, juices & onions, return to pan, add thickener for gravy.