In a medium bowl, combine mirin, minced garlic, grated ginger, and sesame oil. Cut the sirloin steak into cubes and add to the marinade. Cover and refrigerate for at least 30 minutes.

Wash and slice the carrots and zucchini into thin rounds. Quarter the mushrooms and arrange the prepared vegetables on a plate.

Heat a large skillet over medium-high heat, add a splash of oil, then add the carrots, zucchini, and mushrooms. Sauté for 5-7 minutes until tender and caramelized.

Increase heat to high, add the marinated steak to the skillet with vegetables. Sear for about 4-5 minutes until browned to your liking.

Mix the cooked steak with sautéed vegetables and serve over fried rice, drizzling with soy sauce.