Slice the steak against the grain into 1-inch slices. Mix with ½ teaspoon soy sauce, olive oil, half the garlic, and ¼ tablespoon cornstarch, marinate the steak for at least 20 minutes and as long as 8 hours. Coat the steak slices with the remaining cornstarch.

Heat some vegetable oil in a pan or wok at medium high. Cook the steak for 1 minute and then turn the slices and cook for 20 seconds. Remove the steak and let it dry in a bowl with paper towel. Drain almost all the vegetable oil from the pan leaving around 1 tbsp, add the ginger and remaining soy sauce and cook for 10 seconds, add the remaining garlic, water, and brown sugar. Stir until the sugar dissolves and simmer for 1 ½ minutes, add the green onion and steak slices and stir fry for 1 minute.

Fill a bowl with the rice and top with the Mongolian beef, coriander leaves, avocado slices, grated carrot, and green avocado sauce.