Heat oil in 12-inch skillet over medium-high heat. Cook onion, garlic, beef, salt and pepper in oil 7 to 10 minutes, stirring occasionally, until beef is browned.
Spoon beef mixture into 6-quart slow cooker. Stir in carrots, barley and broth.
Cover and cook on Low heat setting 8 to 9 hours.
Increase heat setting to High. Stir in frozen peas and corn. Cover and cook 8 to 10 minutes or until peas and corn are hot.