Biftek Hache a La Lyonnaise

This is a Julia Child's recipe from Mastering the Art of French Cooking, Vol.1 pp. 301-302. I used to make these for company even, they were that good. Have been making them for years. Good, good flavor - don't let the long list frighten you away. The vermouth is the best!

• Ready In: 35 mins
• Serves: 6

Ingredients

• 3⁄4 cup  finely minced yellow onion
• 2  tablespoons butter
• 1 1⁄2 lbs  extra lean ground beef
• 2  tablespoons  softened butter or 2  tablespoons suet or 2  tablespoons  marrow or 2  tablespoons  fresh  pork fat
• 1 1⁄2 teaspoons salt
• 1⁄8 teaspoon pepper
• 1⁄8 teaspoon thyme
• 1  egg
• 1⁄2 cup flour, spread on a plate
• 1  tablespoon butter
• 1  tablespoon  oil
• 1⁄2 cup  beef stock or 1⁄2 cup dry white wine or 1⁄2 cup wine or 1⁄2 cup dry vermouth or 1⁄2 cup red wine or 1⁄4 cup water
• 2 -3  tablespoons butter

Directions

1. Cook the onions slowly in 2 Tablespoons of butter (about 10 mins) until tender not browned.
2. Place onions in mixing bowl. Add the beef, butter (or suet, marrow or pork fat) the seasonings and the egg; mix well.
3. Form into patties 3/4" thick.
4. Cover & refrigerate till ready to use.
5. Just before sautéing, roll the patties lightly in flour.
6. Shake off any excess flour.
7. Place butter and oil in heavy skillet over med-high heat.
8. When butter foam begins to subside, saute the patties for about 3 minutes per side (or more depending upon how you like your burger).
9. Place burgers on serving platter and keep warm while finishing the sauce.
10. Pour fat out of the skillet and discard.
11. Add stock (or wine, vermouth or water) and boil down rapidly.
12. Scraping up the coagulated pan juice till reduced to almost a syrup.
13. Off heat, swirl 2-3 Tablespoons of butter into the sauce - 1/2 Tablespoon at a time until absorbed into the sauce.
14. Pour the sauce over the hamburgers and serve.