sliced beef - 300 grams (thinly sliced sirloin or tenderloin, 300 grams)
all-purpose flour - 2 tablespoons (medium protein flour for marinating beef, 2 tablespoons)
tapioca starch - 1 tablespoon (for marinating beef, 1 tablespoon)
soy sauce - 1 tablespoon (for marinating beef, 1 tablespoon)
water - 4 tablespoons + 400 ml (for marinating beef, 4 tablespoons plus 400 ml for sauce)
white or black pepper - 1/4 teaspoon (optional for marinade, 1/4 teaspoon)
baking powder - 1/2 teaspoon (optional for tenderizing beef, 1/2 teaspoon)
mushrooms - 90 grams (Champignon or Shiitake/Shimeji, sliced, 90 grams)
onion - 1/2 (1/2 medium onion, sliced and diced)
garlic - 2 cloves (2 cloves, pounded and chopped)
celery - 1 stalk (1 stalk, chopped)
dried oregano - 1/2 teaspoon (1/2 teaspoon)
unsalted butter - 1 tablespoon (1 tablespoon)
ketchup - 1 1/2 tablespoons (optional, 1 1/2 tablespoons)
gravy powder or demi-glace powder - 2 tablespoons + 2 tablespoons water (2 tablespoons, diluted with 2 tablespoons water)
cooking oil - 2 tablespoons (2 tablespoons for sautéing)
salt - 1/2 teaspoon (1/2 teaspoon)
sugar - 1/2 teaspoon (1/2 teaspoon, added if ketchup is skipped)
chicken stock powder - 1 1/2 teaspoons (1 1/2 teaspoons)
milk - 300 ml (300 ml, for creaminess)