Combine quinoa with 2 cups water in a medium saucepan and bring to a boil over high heat. Reduce heat to a simmer, cover, and continue cooking until all water is absorbed. In a medium bowl, combine cooked quinoa, dried cranberries, green beans, walnuts, and green onions until well mixed. In a small bowl, whisk the balsamic vinegar, olive oil, and garlic until well blended. Pour over the quinoa mixture. Toss until well blended. Season with salt and pepper, to taste. Chill in the refrigerator for at least 30 minutes before serving.