Cut beef steak lengthwise in half, then crosswise into 1/4-inch thick strips.
Heat 1 teaspoon oil in large nonstick skillet over medium-high heat until hot. Add half of beef; stir-fry 1 to 2 minutes or until outside surface of beef is no longer pink. Remove from skillet. Repeat with 1 teaspoon oil and remaining beef. Remove from skillet; keep warm.
Heat remaining 4 teaspoons oil in same skillet over medium-high heat until hot. Add potatoes. Cook 7 to 8 minutes or until browned and crisp-tender, stirring occasionally. Carefully stir in salsa, red pepper and garlic salt. Reduce heat to medium-low. Cook, covered, 10 minutes, stirring occasionally. Return beef to skillet. Add corn; cook 2 minutes. Remove from heat.
Stir in avocado. Serve with sour cream and cilantro.
Nutrition information per serving: 388 Calories; 153 kcal Calories from fat; 17 g Total Fat; 5 g Saturated Fat; 5 g Monounsaturated Fat; 78 mg Cholesterol; 778 mg Sodium; 29 g Total Carbohydrate; 6 g Dietary Fiber; 31 g Protein; 3.1 mg Iron; 10.4 mg Niacin; 1.1 mg Vitamin B6; 1.5 mcg Vitamin B12; 5.7 mg Zinc; 32.2 mcg Selenium; 134.1 mg Choline;