Place the beef in a bowl. Add the salt and pepper. Mix well. Add the starch and mix to coat every sliced of beef.
In a wok or frying pan, heat the cooking oil to smoking point.
Spread the beef in the hot oil. Sprinkle in the minced garlic. Cook the beef until the undersides are browned then flip them over to brown the opposite side.
Pour in the soy sauce and chili sauce. Sprinkle in the sugar. Toss a few times.
Add the mushroom slices, carrot and scallions. Stir fry for another half a minute.
Serve the Mongolian beef barbecue over rice sprinkled with toasted sesame seeds.