Combine the first 5 ingredients in a small bowl, and stir well with a whisk.
Heat vegetable oil in a large nonstick skillet coated with cooking spray over medium-high heat. Add mushrooms; sauté for 6 minutes or until tender. Remove from heat; add maple mixture, tossing to coat. Combine greens, onions, and cilantro in a large bowl. Add mushroom mixture, tossing to coat. Serve immediately.