Beef Stroganoff Sandwiches

Directions

1. Thinly slice the steak crosswise into 1/8 thick slices. It helps to put it in the freezer for 30-45 minutes - not enough to freeze it much, but enough to make slicing easier.
2. Cut the baguettes lengthwise between the top and bottom crust, for sandwiches. Cut 3 4-inch / 10 cm pieces for 3 smaller sandwiches, or 2 6-inch / 15 cm ones for bigger appetites. Toast them, if you like.
3. Slather the top half of each lightly with mayonnaise to taste.
4. In a non-stick skillet, melt half of the butter over medium-high heat until foamy and very hot. Add the steak slices and quickly toss, without stopping, just until most of it loses its pink color. Immediately remove from the heat and divide the steak, with the cooking juices, directly onto the bottom halves of the cut bread. (You want the bread to soak up all those luscious juices.)
5. Without cleaning the pan, put the mushrooms and onions into the skillet with a generous pinch of salt, turn the heat to medium, splash a few tablespoons of water into the skillet, and tightly cover the pan. Cook over medium heat, without disturbing it, for 5 minutes.
6. Meanwhile, whisk together the sour cream, wine or vermouth, Worcestershire sauce, and mustard.
7. Remove the lid and toss the onions and mushrooms. Add the remaining 2 tablespoons of butter. When the butter has melted, toss it with the onions and mushrooms. Cook without stirring for another minute or two, or until the onions are brown (however dark you like them) and the onions are soft.
8. Turn the heat off for about 15 seconds. (If the pan is too hot, the sauce will evaporate so quickly it practically disappears.) Stir in the sour cream sauce and turn the heat back up to medium, stirring evenly to distribute the sauce. Cook for another 10 seconds. Test for salt and correct. Grind on some black pepper to taste and give it all another quick stir.
9. Pile the mushrooms and onions on the steak that’s on the sandwiches. Scatter arugula on top of that and cover with the prepared top pieces of bread.
10. Press down gently for 3 or 4 seconds, serve, and enjoy ;o)
11. N.B. This is also good using room temperature leftover roast chicken instead of beef. Increase the sour cream by two tablespoons, and toss the chicken with the onions and mushrooms at the last minute, right before piling onto the bottom pieces of bread.
12. o make this to serve over toast or noodles, follow the instructions above, but set the meat aside in a bowl while cooking the onions and mushrooms. Whisk about a cup of stock into the sour cream sauce, with an extra 2 - 3 tablespoons of sour cream and an extra dash of Worcestershire sauce, before adding the sauce to the pan. Stir it well, bring to a simmer, and cook for about a minute over medium heat before adding the beef or chicken back in, along with any accumulated juices. Turn the heat off and serve immediately. (Do not cook the meat any further, or it will be tough.)