Stack beef steaks; cut lengthwise in half, then crosswise into 1-inch wide strips. Toss with garlic and oregano.
Heat 2 teaspoons oil in large nonstick skillet over medium-high heat until hot. Add onion; stir-fry 3 to 4 minutes. Remove.
Heat 1 teaspoon oil in same skillet over medium-high heat until hot. Add 1/2 of beef; stir-fry 1 minute or until outside surface of beef is no longer pink. (Do not overcook.) Remove. Repeat with remaining beef.
Return beef and onion to skillet; heat through. Season with salt and pepper. Serve in pita pockets with tomatoes, cucumbers and dressing.
Nutrition information per serving: 483 Calories; 189 kcal Calories from fat; 21 g Total Fat; 4.3 g Saturated Fat; 0.2 g Trans Fat; 1.1 g Polyunsaturated Fat; 4.9 g Monounsaturated Fat; 66 mg Cholesterol; 756 mg Sodium; 42 g Total Carbohydrate; 2.7 g Dietary Fiber; 30 g Protein; 4.1 mg Iron; 593 mg Potassium; 7.7 mg Niacin; 0.6 mg Vitamin B6; 2.8 mcg Vitamin B12; 6.6 mg Zinc; 50.2 mcg Selenium; 104.9 mg Choline;