If using, in a small mixing bowl, mix ½ teaspoon baking soda with a tablespoon of water to form a slurry. Toss beef with baking soda mixture and ½ teaspoon salt in a large bowl until thoroughly combined. Set aside.
Heat 1 tablespoon of the oil in a hot frying pan and add the beef. Stir over high heat until golden brown. Using a metal colander, drain any fat or liquid from the meat and return it to the pan. Sprinkle the flour over the meat and coat well. Cook for 1to 2 minutes or until no raw flour is visible. Remove from the pan and set aside.
Lower the heat to medium, and heat the remaining oil in the same pan. Add the onions, celery, and carrots to the pan and fry until they begin to soften. Return the beef to the pan.
Add the stock and soy sauce to the pan, stirring constantly to avoid any lumps. Raise the heat to high, bring to a boil, then add the mushrooms and parsley. Lower the leat to low, cover with a lid, and simmer for 30 minutes or until the mixture is tender. Taste for seasoning and season with salt and pepper as needed.
While the filling cooks, start the potatoes – Boil the potato slices in salted water for about 4-5 minutes or until they start to soften. Drain them carefully into a colander and leave to cool.
Preheat the oven to 425f/220C.
Pour the beef mixture into a 3 to 3.5 quart casserole dish. Arrange a layer of the blanched potato on top of the beef mixture.
Thoroughly mix the flour into the cream (being sure not to leave any lumps). In a saucepan, heat up the cream garlic, nutmeg, and some salt and pepper. bring to a simmer and allow to thicken.
Pour half of the cream mixture over the first layer of potatoes already in the pan. Arrange the remaining potatoes on top, seasoning between the layers. Pour over the remaining cream and sprinkle over the cheese.
Bake in the preheated oven for about 30 minutes or until golden brown.
Notes
Don’t skip the baking soda step. This will ensure your beef stays nice and moist.
When browning the beef, only cook until the pink is gone. You don’t want to overcook it.
For extra depth of flavor, allow the vegetables to brown once softened and then scrape the pan to remove any crispy bits when adding the stock.
Allow the sauce to thicken well before assembling. You don’t want a soupy mess.