Chicken and Potatoes Dijon

1 1/3 pounds potatoes -- (4 medium)
4 green onions -- sliced
2 cloves garlic -- minced
1 tablespoon Dijon-style mustard
2 teaspoons chopped fresh tarragon or 1/2 to 1 teaspoon dried tarragon
2/3 cup dry white wine or chicken broth
1/4 cup light sour cream
4 4-oz each boned and skinned chicken breast halves
salt and pepper -- to taste

Pierce potatoes with tines of fork; micro-bake on HIGH ten minutes; cut into 1/2 inch cubes. Spray a 12-inch nonstick skillet with vegetable cooking spray; add potatoes and onions and cook over medium heat, tossing occasionally, adding more vegetable cooking spray as necessary, 10 minutes. Push potatoes to side of skillet to allow room for chicken. Add chicken to skillet; cook with potatoes, tossing potatoes occasionally, about 15 minutes, until potatoes are tender and chicken juices run clear. Season with salt and pepper. Remove chicken and potatoes to platter; keep warm. Add garlic to skillet; sauté, stirring, 1 minute. Add mustard, tarragon and wine; cook on high heat until reduced by half. Remove from heat; whisk in sour cream. Season with salt and pepper. Pour sauce over chicken; serve immediately.