Cut bell peppers in half lengthwise; discard seeds and membranes. Place pepper halves, skin sides up, on a foil-lined baking sheet; flatten with hand. Broil 15 minutes or until blackened. Place in a zip-top plastic bag; seal. Let stand 15 minutes. Peel and chop.
Prepare grill to medium-high heat.
Cook orzo according to package directions, omitting salt and fat. Drain. Place orzo in a large bowl; drizzle with 1 tablespoon oil. Cool slightly.
Place corn and red onion on grill rack coated with cooking spray; grill 5 minutes or until lightly browned, turning occasionally. Cut kernels from ears of corn; chop red onion. Add bell pepper, corn, red onion, 2 tablespoons oil, green onions, and remaining ingredients to orzo. Toss gently to combine.