In a medium bowl, combine mirin, garlic, ginger, and sesame oil.
Add the cubed sirloin steak and toss until evenly coated.
Cover and refrigerate for at least 30 minutes to allow the flavors to develop.
While the steak marinates, wash and prepare the vegetables by slicing the carrots and zucchini and quartering the mushrooms.
Heat a large skillet over medium heat and add a small drizzle of oil.
Add the vegetables and sauté for 5 to 7 minutes until tender but still slightly crisp.
Increase the heat to medium-high.
Add the marinated steak and cook for 4 to 5 minutes, stirring occasionally, until it reaches your preferred doneness.
Combine the cooked steak and vegetables in the skillet.
Divide the fried rice among serving bowls.
Top with the steak and vegetable mixture.
Drizzle with soy sauce and serve immediately.
These Hibachi Steak Bowls are best enjoyed hot and fresh for maximum flavor.