Combine first 4 ingredients in a large bowl; stir with a whisk. Set aside.
Heat 1 teaspoon oil in a large Dutch oven over medium-high heat; add half of the beef, browning on all sides. Remove from pan. Repeat procedure with remaining oil and beef. Return beef to pan; add water mixture, onions, garlic, cinnamon, and ginger. Bring to a boil; cover, reduce heat, and simmer 2 hours or until beef is tender. Discard ginger slices and cinnamon. Stir in spinach; cook 3 minutes or until wilted. Serve over noodles.