Tie green beans in small bundles of five or six with chives that have been boiled for 5 seconds.
Melt butter in a small saucepan over medium heat; reduce heat to low, and keep warm. Process egg yolks, next 3 ingredients, 1 Tbsp. water, and, if desired, hot sauce in a blender or food processor 2 to 3 minutes or until pale and fluffy. With blender running, add melted butter in a slow stream, processing until smooth. Serve warm with beans.