Toss the steak with the corn starch in a large bowl and set aside.
Over medium heat, add the vegetable oil and onions to a sauce pan. Sauté for two minutes until onions are translucent.
Add the carrots to the onions and sauté for 3-4 minutes until tender.
Next, add the garlic, ginger, and chili flakes. Stir into the carrots and onions. Cook for 1-2 minutes.
Lastly, add the soy sauce, vinegar, sesame oil, black pepper, brown sugar, and sesame seeds. Whisk together.
Lower the heat to a simmer and allow the sauce to slightly thicken.
In the meantime, bring about 2-3 cups of vegetable oil to optimum frying temperature in a deep skillet. Shake the excess corn starch off the beef and fry each piece in batches until crispy. This process takes about 3-4 minutes. Drain the fried beef on paper towels.
Toss the fried beef with the sauce mixture. Garnish with green onions. Serve immediately.