Melt butter in medium nonstick saucepan over medium-low heat. Stir in flour with wire whisk; cook and stir 1 to 2 minutes or until smooth and bubbly. Gradually add warm half-and-half, cooking and stirring 2 to 3 minutes or until mixture boils and thickens. Remove from heat. Stir in lemon juice, sherry, mustard, 1/4 teaspoon salt and hot pepper sauce.