In a large deep fry pan, heat 1 tablespoon of olive oil, then add the sliced mushrooms, and fry on low to medium heat, until the mushrooms change colour and become soft, this will take about 3-5 minutes.
When done, transfer the cooked mushrooms and any juice you get from them to a bowl, and put aside for later.
In the same pan cook the meat in two batches: Heat 1 tablespoon of olive oil, add quarter of the thinly cut gravy beef and fry until brown all over. Transfer the meat and juices to a plate. Repeat for the remaining meat.
Add a little more oil (about ½ teaspoon) to the fry pan. Add the sliced onions and garlic. Fry for 2 -3 minutes, or until the onions become soft.
Return all the browned meat and its juices to the pan with the onions. Add the red wine, water and 2 tablespoons of soy sauce and stock powder, bring to the boil, cover with a lid, then reduce the heat.
Allow meat to simmer for about 1 hour, or until the meat is soft and tender.
Once the meat is tender and soft, stir in the cooked mushrooms, fresh cream, and sour cream to the meat. Gently simmer for about 5 minutes, taste for salt – adding the remaining soy sauce and a little salt if needed. Season with freshly ground pepper.
If you think the sauce is too thin and would like a thicker sauce, you can mix 2 teaspoons of cornflour with a little water and slowly pour and stir this into the Stroganoff, allow to cook for a minute on medium to low heat until the sauce thickens.
Serve with pasta, salad, or steamed vegetables.