Mix yum yum sauce ingredients together and refrigerate until serving.
Heat cast iron skillet over high heat 2 minutes. Add sesame oil and sear steak cubes undisturbed 90 seconds per side.
Add butter, garlic, and soy sauce. Toss steak to coat and cook 60 seconds more. Remove and tent with foil.
Cook vegetables in the same pan with sesame oil, soy sauce, and butter over high heat 4 to 5 minutes until lightly charred.
Melt butter in a large skillet, add peas and carrots, scramble eggs on the side, then add rice and fry 3 to 4 minutes with soy sauce and sesame oil.
Build bowls with fried rice, steak bites, and vegetables. Drizzle yum yum sauce over the top and garnish with sesame seeds and green onion.