Step 1

Combine wine, vinegar, and shallot in top of a double boiler. Simmer until reduced by half and then let mixture cool.

Step 3

Once cooled, place mixture, egg yolks, pepper, garlic salt, and tarragon leaves in food processor (or blender). Blend for about 10 seconds.

Step 5

Melt butter in microwave for a 1:15, or until slightly bubbling, but be careful not to burn! Then remove the center stopper from the food processor (or blender) and slowly pour the butter through the opening while the motor is running. This process should take about 30 seconds.

Step 7

Process for another 10 seconds after all the butter has been added. The sauce should be the consistency of a thin mayonnaise. If not, blend for another 5 seconds. Serve immediately.