In a large non-stick skillet, heat oil over medium heat. Add chicken, meaty-side down; cook until browned, about 8 minutes. Turn the chicken; cover and cook until no longer pink near bone, about 12 minutes.

While chicken is cooking, in a blender or food processor fitted with a metal blade, process green onions, parsley, broth, brandy, cornstarch, mustard, and salt until smooth.

Transfer chicken to a serving platter. Add margarine and broth mixture to skillet. Cook until slightly thickened, about 2 minutes. Remove from heat; stir-in lemon juice. Spoon sauce over chicken and serve immediately.