Combine all of the dressing ingredients in a blender and mix until smooth. Or, for a more textured dressing, whisk the ingredients together in a small bowl. In a large bowl, combine the spinach, chicken, cucumber, grapes and soybeans. Toss with the dressing and add salt and pepper if desired. Serve immediately.
Nutritional analysis per serving: Calories 427; Protein 38 g; Carbohydrate 25 g; Fat 21 g; Saturated Fat 3 g; 43% Calories from Fat; Cholesterol 68 mg; Sodium 718 mg; Fiber 3.3 g.