Combine first 6 ingredients in a small saucepan; bring to a boil. Reduce heat to low, and simmer until liquid is reduced by half; cool.
Beat yolks and water in top of a double boiler with a wire whisk. Gradually add vinegar mixture, beating well. Place over simmering water and cook, beating constantly with wire whisk, until mixture thickens.
Remove from heat, and add butter, 1 tablespoon at a time, beating constantly, until sauce is smooth and thickened. Stir in parsley, lemon juice, and salt and pepper. Serve warm with baked or broiled fish or shellfish.