Preheat oven to 400 degrees F. Cut the zucchini and red bell pepper lengthwise. Brush the vegetables with olive oil on both sides. Sprinkle with dried oregano, salt and black pepper.
Spread out the seasoned vegetables in a single layer onto a large baking pan (do not crowd). Bake in the preheated oven until vegetables are cooked through, about 30-35 minutes. Remove vegetables and let them cool.
When they are cool enough to handle, cut the vegetables into bite-sized pieces and set aside.
Meanwhile bring a pot of salted water to a boil. Add the orzo and cook uncovered, over high heat until al dente, cooked through but still a bit firm, stirring occasionally (or cook the orzo according to the package directions). Drain the orzo in a colander and rinse with cold water.
For dressing, whisk the balsamic, soy sauce and olive oil in a small bowl. Season with salt and black pepper, to taste.
Place the orzo, sliced green onion, zucchini, bell pepper, chopped cilantro and black olive in a salad bowl. Pour the dressing over the salad and gently toss together. Taste and adjust seasonings.
Right before serving sprinkle feta cheese on top.