Cut beef Round Tip Steak into 1-1/4-inch pieces. Combine marinade ingredients. Place beef and marinade in food-safe plastic bag; turn to coat. Close bag securely and marinate in refrigerator 6 hours or as long as overnight, turning occasionally.
Heat 2 teaspoons oil in large nonstick skillet over medium heat until hot. Add mushrooms; cook and stir until tender. Remove and keep warm. Meanwhile cook rice according to package directions, omitting salt and butter. When rice is done, stir in mushrooms.
Soak eight 9-inch bamboo skewers in water 10 minutes; drain. Remove beef from marinade; discard marinade. Alternately thread beef, onion, squash and pepper evenly onto skewers. Place on grid over medium, ash-covered coals. Grill, covered, 8 to 10 minutes (over medium heat on preheated gas grill, covered, 9 to 10 minutes) for medium rare (145°F) to medium (160°F) doneness, turning occasionally.
Serve kabobs over wild rice.
Nutrition information per serving: 390 Calories; 81 kcal Calories from fat; 9 g Total Fat; 2 g Saturated Fat; 0 g Trans Fat; 2.9 g Polyunsaturated Fat; 2.5 g Monounsaturated Fat; 75 mg Cholesterol; 410 mg Sodium; 46 g Total Carbohydrate; 3 g Dietary Fiber; 30 g Protein; 4 mg Iron; 402.9 mg Potassium; 12.5 mg NE Niacin; 0.8 mg Vitamin B6; 1.9 mcg Vitamin B12; 4.4 mg Zinc; 26.5 mcg Selenium; 77.8 mg Choline;