Place sour light cream in a saucepan. Add crushed garlic. Simmer very gently for about 2 minutes, stirring. Do not boil. Add lemon juice, lemon rind, mushrooms and parsley. Continue simmering for about 5 minutes or until thickened slightly. Chill before serving.
Coat whiting fillets in flour.Dip into beaten egg. Coat lightly with breadcrumbs. Heat oil in frying pan. Quickly cook fish, (2 minutes each side) until golden. Serve immediately with chilled dressing.
Accompany with a green salad, sautéed pumpkin and potato slices, if desired.