Preheat oven to 375°.
Scoop out pulp from 8 of the zucchini halves and arrange on baking sheet.
Coarsely chop the two remaining halves including pulp. Place oil in nonstick skillet and heat over medium-high heat
Add chopped zucchini and onion, cook until tender.
Add red pepper, garlic and oregano. Cook, stirring frequently - about 3- 5 minutes and cool slightly.
Evenly spoon vegetable mixture into zucchini halves. Top with cheese.
Bake 30 minutes, or until tender.