Whisk flour, chicken stock and reserved mustard until blended. Place skillet on stove-top burner. Add shallots; cook and stir on medium heat 3 to 4 min. or until crisp-tender. Stir in wine; bring to boil, stirring constantly. Continue to cook 2 to 3 min. or until sauce is reduced by half, stirring constantly. Gradually stir in flour mixture. Bring to boil, stirring constantly; cook and stir 3 min. or until thickened. Remove from heat. Stir in herbs.