Place chicken in a plastic bag set in a deep bowl.
In a small bowl stir together vinegar, oil, mustard, sugar, salt, paprika, and pepper. Pour over chicken; close bag. Marinate chicken in the refrigerator for at least 2 hours or up to 5 hours, turning bag frequently.
Meanwhile, in a large bowl combine spinach, tomatoes, carrot, jicama or water chestnuts, and radishes. Cover and chill until serving time.
Spray a cold wok or large skillet with nonstick spray coating. Preheat over medium-high heat. Drain chicken, reserving marinade. Stir-fry chicken for 2 to 3 minutes or until cooked through. Add marinade and heat until boiling.
Pour hot chicken mixture over salad mixture. Toss to combine. Serve immediately. Makes 4 servings.