1. Heat a grill or grill pan over medium-high heat.
2. Place corn on grill rack; grill 20 minutes or until here-and-there charred, turning occasionally. Place in a large bowl; cover with foil. Leave in a warm location 10 minutes.
3. Place peppers on grill rack, and grill 4 minutes on each side; cut into 1-inch pieces.
4. Grill onion slices 3 minutes on each side; chop.
5. Cut corn kernels off cobs, encouraging clusters to stay intact, if possible.
6. Combine onion, jalapeño, chives, cream, oregano, vinegar, black pepper, salt, and garlic in a large bowl. Add peppers and corn; toss gently to coat. Gently fold in chicken. Serve warm.