Spray 4- to 5-quart slow cooker with cooking spray. Cut beef into 1-inch pieces; place in slow cooker. Stir in remaining stew ingredients except flour.
Cover; cook on Low heat setting 8 to 10 hours.
In small bowl, mix 1/4 water and the flour; gradually stir into stew. In another bowl, stir baking mix, 1/2 teaspoon thyme and the sage. Stir in milk just until moistened. Drop dough by spoonfuls onto hot stew.
Increase heat setting to High. Cover; cook 25 to 35 minutes or until toothpick inserted in center of dumplings comes out clean. Serve immediately.