In 2-quart saucepan, heat sauce just to a low simmer over medium-low heat, stirring constantly; do not boil. Pour into fondue pot or heatproof serving bowl, and keep warm over low heat. Bagna cauda sauce, like fondue, must be served over heat to maintain its smooth, creamy texture. Stir in lemon peel. Sprinkle with parsley, and serve with artichoke hearts. If sauce separates, stir until smooth.