Sprinkle beef pieces with 1/4 teaspoon of the seasoned salt and 1/4 teaspoon of the garlic-pepper blend. In 12-inch nonstick skillet, cook beef over medium-high heat 3 to 4 minutes, turning once or twice, until brown and desired doneness. Remove from skillet; keep warm.
In same skillet, melt butter over medium heat. Cook stir-fry vegetables in butter 2 minutes, stirring frequently. Add potatoes; sprinkle with remaining 1/2 teaspoon seasoned salt and 1/4 teaspoon garlic-pepper blend. Cook uncovered 8 to 10 minutes, stirring frequently, until tender.
Place beef in skillet with potatoes, pushing potatoes around beef. Cook 1 to 2 minutes, turning beef once, until thoroughly heated. Sprinkle with cheese; cover and heat until cheese is melted.