In a mixing bowl, combine mirin, minced garlic, freshly grated ginger, sesame oil, and soy sauce to create a flavorful marinade. Slice the sirloin beef thinly and coat each piece thoroughly. Cover and let marinate for 30 minutes.

Prepare the fried rice according to package instructions, typically cooking in a skillet for 5-7 minutes until heated through. Set aside in a serving bowl.

In a large skillet or wok, heat oil over medium-high heat. Add carrots, zucchini, and mushrooms, stirring for 5-6 minutes until the veggies are tender but still vibrant.

Remove the veggies and in the same pan, add the marinated beef (reserving some marinade). Cook for 4-5 minutes until browned and cooked to your liking.

To assemble, layer fried rice in serving dishes, top with sautéed vegetables and cooked beef. Drizzle any reserved marinade over top.