Season flour, if desired, with salt and ground black pepper. Dip chicken in egg, then flour mixture; set aside.
Melt 2 tablespoons margarine in deep 12-inch nonstick skillet and cook chicken over medium-high heat, turning once, about 5 minutes. Remove chicken and set aside.
Melt remaining 1 tablespoon margarine to same skillet and cook vegetables, stirring frequently, until crisp-tender, about 4 minutes. Stir lemon juice, water and Knorr® Homestyle Stock - Chicken skillet until Stock is melted. Bring to a boil over high heat, stirring frequently. Return chicken to skillet. Reduce heat to low and simmer until chicken is thoroughly cooked, about 3 minutes. Garnish with parsley.