This turned out so well, that I am documenting it now even though I did not take a picture of the final product.  I read through several recipes for pan sauces for steak and pieced together the following combination for 2 servings:

11 oz. sirloin steak, about 1 inch thick

oil

1 large onion, thinly sliced

butter

Flour, ` 2 tsp.

Brandy

1 tsp. Better than Bouillon in a cup of water

1/4 cup heavy cream

2 tsp. Dijon mustard

Fish sauce, and black pepper to taste

Several hours before cooking, season the two sides of the steak and put it in the refrigerator on a cake rack over a plate.  Initially the seasoning will draw juices out of the steak, but after a while they will be reabsorbed.  Airing in the refrigerator like this will dry the surface of the steak, and that will help the steak develop a good crust when it is later pan fried.

Put a cast iron frying pan on the burner on high heat.  Add a little oil and wait until it is good and hot.  Add the steak, and cook over high heat, flipping it about once a minute until the temperature in the middle of the steak is 130 degrees on an instant read thermometer.  This took about 8 minutes, but it will vary depending on the thickness of the steak.  After a few minutes, you may need to turn the heat down if the crust seems to be over developing.  By frequently flipping the steak, you are promoting even cooking, in the same way that a rotisserie works.

When the steak is done, put it on a plate covered with aluminum foil in a warn oven to stay warm while you make the pan sauce.

If there is excessive oil in the pan pour it out.  Turn the burner down to medium-low, add about a tablespoon of butter and the sliced onions, toss them in the pan, and then cook slowly until golden.  Sprinkle in the flour and continue to cook until the flour has colored.  Do not let it burn.

Deglaze the pan with a slug of brandy, stirring up the frond on the pan.  Add the Better than Bouillon and water and stir.  Cook until a thickened sauce has formed.  Add the cream and mustard and stir until well blended.  Taste the sauce, adding black pepper, and a sprinkle of fish sauce, if it could use some more salt.  Add a second slug of brandy (` 1 Tbs.) and any juices from the steak which have collected on the plate while the steak rested.  Stir them in.

Cut the steak in half, plate it, and cover with the onion cream pan sauce.  Enjoy.