Spray large nonstick skillet with nonstick cooking spray. Heat over high heat until hot. Sprinkle both sides of pork chops lightly with salt and pepper; add to skillet. Cook 2 minutes on each side or until browned. Remove chops from skillet; cover to keep warm.
Add onion and 2 tablespoons of the water to same skillet; cook over medium heat for 2 minutes, stirring frequently. Add chops, mushrooms, thyme and beer. Reduce heat to medium-low; cover and cook 8 to 11 minutes or until chops are no longer pink in center.
In small bowl, combine remaining 2 tablespoons water and flour; blend well. Add to skillet; cook and stir until thickened. Serve mushroom mixture over chops.