Ledbetter Beef Filet with Béarnaise Sauce

Ingredients
2 Tbsp. White Wine Vinegar
2 Tbsp. Dry White Wine
1 Tbsp. White Onion diced
1 Tbsp. fresh Tarragon
8 Tbsp. unsalted butter (1 stick)
3 egg yolks
1/8 tsp. salt
Dash pepper
COOKING INSTRUCTIONS
In a small ovenproof bowl melt butter in small saucepan, over high heat combine vinegar, wine, onion and tarragon. Boil approximately 1 minute to reduce liquid. Remove from heat and allow to cool to room temperature. Meanwhile, fill bottom of double boiler with water and bring almost to a boil. Lower heat so that water is hot but not boiling. In top of double boiler, combine egg yolks and onion mixture. Place top of double boiler over bottom and gradually wisk in the melted butter in a slow, steady stream. Continue stirring with the wisk until sauce is thick. Adjust salt and pepper. Serve immediately.