Season the steak: Pat the sirloin dry and season both sides with salt, black pepper, garlic powder, onion powder, and red pepper flakes.
Sear the steak: Heat a large skillet over medium-high to high heat. Add olive oil and sear the steak until browned and cooked to your preferred doneness.
Rest and slice: Transfer the steak to a cutting board and let it rest for about 5 minutes. Slice thinly against the grain.
Make the sauce: Whisk together soy sauce, sesame oil, rice vinegar, water, honey, ginger, garlic, and red pepper flakes in a small bowl.
Warm the grains: Heat the cooked brown rice and red quinoa over medium heat. Stir in sesame oil and soy sauce and warm until heated through.
Cook the vegetables: Heat cooking oil in a skillet or wok. Add onion and garlic, followed by mushrooms, carrots, snap peas, and baby broccoli or asparagus. Cook until tender-crisp.
Add the bok choy: Stir in the chopped bok choy near the end and cook briefly so it remains slightly crisp.
Build the bowl: Add the warm brown rice and quinoa to serving bowls. Top with the cooked vegetables and sliced steak.
Add the sauce: Drizzle the homemade sesame-soy sauce over the bowl. Finish with green onions and sesame seeds.
Serve: Serve the Yard House steak bowl immediately while the steak and grains are warm.