Easy side: Toss 1 (5-oz.) head Bibb lettuce with 1/2 cup drained mandarin oranges. Serve with bottled ginger dressing.
Preheat grill to 350º to 400º (medium-high) heat. Whisk together first 6 ingredients in a small bowl. Pour half of olive oil mixture into a shallow bowl or zip-top plastic freezer bag; add chicken, turning to coat. Cover or seal, and let stand 10 minutes. Pour remaining olive oil mixture into another bowl or freezer bag; add bell pepper, tomatoes, and mushrooms, and toss to coat; cover or seal, and let stand 10 minutes.
Remove chicken and vegetables from marinade, discarding marinade. Thread chicken onto 8 skewers. Thread vegetables alternately onto remaining 8 skewers.
Grill kabobs, covered with grill lid, 10 to 12 minutes or until chicken is done and vegetables are tender, turning occasionally. Remove kabobs from grill. Let stand 5 minutes before serving.
This was very easy and delicious. I used frozen chicken breasts and, as I didn't have any red wine vinegar, substituted balsamic.