- Combine soy sauce, wine, cilantro, onion powder and black pepper.
- Cut squash and bell pepper into 1-inch pieces. Bring about 1 quart water to boil in large saucepan; add squash. Remove pan from heat; cover and let stand 5 minutes.
- Drain squash; rinse immediately with cold water until completely cool. Drain thoroughly.
- Thread squash alternately with pepper on skewers, ending with mushroom.
- Place steak and vegetable kabobs in large shallow pan; pour marinade over all. Brush steak and kabobs thoroughly with marinade. Marinate about 30 minutes, turning steak and kabobs over occasionally.
- Place steak and kabobs on grill over medium coals. Grill 16 to 20 minutes to desired doneness, turning over occasionally. *Soak bamboo skewers in water 30 minutes to prevent burning.