Preheat oven to 400ºF (200ºC).
Combine all vegetables (except spinach) in large bowl and stir.
Add salt, pepper, oregano, and olive oil for the salad and stir.
Spread vegetables on baking sheet and bake for 40 minutes.
To prepare the dressing, combine olive oil, balsamic vinaigrette, and maple syrup in a small bowl and stir until well-combined.
In a bowl, add spinach and any other greens you prefer. Sprinkle roasted vegetables and feta cheese over the top.
Drizzle dressing over salad.
