Marinate the Steak: In a bowl, whisk together mirin, minced garlic, grated ginger, and sesame oil. Place sirloin steak in a resealable bag, pour marinade over, seal, and marinate for at least 30 minutes.

Sauté Vegetables: Heat oil in a skillet over medium-high heat. Add sliced carrots, zucchini, and mushrooms, sautéing until tender, about 5-7 minutes. Transfer to a plate and cover to keep warm.

Cook the Steak: In the same skillet, increase heat to high, add marinated sirloin steak, and sear for 3-5 minutes per side until a golden-brown crust forms.

Assemble Bowls: Allow steak to rest, then slice against the grain. Layer fried rice in bowls, top with sautéed vegetables and sliced steak for presentation.

Serve: Garnish with sesame seeds and green onions. Optionally serve with Yum Yum sauce or pickled ginger.