1. Preheat oven to 450°.
2. Combine tomatoes and 2 tablespoons balsamic vinaigrette on a jelly-roll pan, tossing well to coat. Bake at 450° for 15 minutes or until shriveled and roasted. Cool completely (about 15 minutes).
3. Combine cooled tomatoes, spinach and arugula mix, and next 4 ingredients in a large bowl, tossing well to combine. Add remaining dressing; toss well to coat.