In a large skillet heat the 2 tablespoons oil over medium-high heat. Add squash; cook until crisp-tender, stirring occasionally. Stir in 1/2 teaspoon salt and 1/2 teaspoon pepper. Remove from heat; let cool. Set aside.
Meanwhile, place quinoa in a strainer; rinse with cold water. In a large saucepan combine the 3 cups water and 1/8 teaspoon salt. Bring to boiling over medium-high heat. Add quinoa. Reduce heat. Simmer, covered, about 15 minutes or until the grain becomes translucent, the white germ forms a spiral on the exterior of the grain, and most of the liquid is absorbed.
For dressing, in a small bowl whisk together lemon peel, lemon juice, the 1/3 cup grapeseed oil, the honey, and garlic. In a large bowl combine undrained cooked quinoa, squash, mint, and arugula. Pour dressing over quinoa mixture; toss gently. Season to taste with salt and pepper.