3/4 cup yellow onion, finely minced
  2 tablespoons butter

  1 1/2 lbs lean ground beef
  2 tablespoons butter, softened
  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, beef bouillon, dry white wine, dry white vermouth, red wine, or 1/4 cup water
  2-3 tablespoons butter, softened
  2 tablespoons green herbs, minced (such as parsley, chives, tarragon, or chervil)