1-First, wipe the mushrooms with a paper towel to remove dirt, then slice them no more than 3 mm thick or chop some for added texture. This step ensures they cook evenly and absorb flavors well. Heat the vegetable oil and butter in a large shallow pan until melted, setting the stage for a flavorful base.

2-Next, add the sliced mushrooms and cook over fairly high heat for about 10 minutes, stirring occasionally and more frequently toward the end. This helps the moisture absorb and the mushrooms turn lightly browned for better taste. Once done, stir in the salt, onion granules, white pepper, and soy sauce, then pour in the warm water and stir to combine.

3-In a separate bowl, mix the sour cream, flour, and 1 tablespoon cold water until smooth, then add 2 tablespoons of the mushroom sauce from the pan and stir. Return this mixture to the pan and stir thoroughly, simmering for 1-2 minutes while stirring often. Finally, remove from heat, adjust seasoning if needed, and stir in the chopped parsley before serving.