Cut liver into serving pieces and pat dry with paper towels. Combine flour, salt, pepper, and paprika in a pie plate. Dip liver in mixture to coat both sides well. Heat margarine and vegetable oil in a heavy skillet. Saute garlic until golden. Add liver and brown quickly, about 2 minutes for each side. Remove to a warm platter and keep warm while preparing sauce. For sauce, melt margarine in the same skillet and stir in onion; saute until cooked through. Mix together water, cornstarch, Worcestershire sauce, and mustard. Blend mixture into skillet and cook, stirring, for 2 minutes. Add pickle and cook 1 minute. Add liver to sauce and heat through. Serve immediately.