Meanwhile, in a large skillet, heat 2 tablespoons olive oil over high heat. Add the zucchini flesh and onion and cook, stirring, until softened, about 5 minutes. Add the tomatoes and cook until softened, about 5 minutes. Push the vegetables to the side of the pan, add the remaining 1 tablespoon oil and the bread crumbs, and toast the bread crumbs for 2 minutes. Remove from the heat, stir in the nuts and oregano, then combine with the vegetables; season with salt and pepper.