Preheat oven to 350 F (180 C). Heat olive oil in saucepan over medium-high heat. Add onion and garlic, and cook 3 min., stirring, until onions are translucent.
Stir quinoa into saucepan mixture. Pour in chicken broth and bring to a boil. Reduce heat to low, cover and cook 15 min., or until liquid is absorbed and quinoa is tender. Add eggplant, zucchini, salsa, corn, oregano and chili powder; continue cooking, stirring gently, about 5 more min. until mixture is moist but not runny; season with salt to taste.
Stuff each halved pepper with quinoa mixture. Set in lightly oiled ovenproof dish. Sprinkle cheese. Bake about 25 min., or until peppers are tender-crisp. Broil briefly to brown cheese.
When you cook quinoa, make extra and freeze it to use as time-saver in other quinoa dishes.