Combine Greek yogurt, sriracha, rice vinegar, 1 tsp sesame oil, Dijon mustard, garlic, 1/2 tsp salt, and 1/2 tsp pepper in the blender. Blend until smooth.

Taste the yum yum sauce and adjust seasoning if needed. Set it aside.

Pat the steak dry and cut it into 1 1/2-inch chunks. Place the steak in the mixing bowl.

Add 2 tbsp rice vinegar, 1/2 tbsp sesame oil, soy sauce, ginger, garlic powder, onion powder, 1/2 tsp salt, and 1/2 tsp pepper to the steak. Toss until coated.

Marinate the steak for at least 30 minutes. Refrigerate it for up to 4 hours for deeper flavor.

Heat the cast-iron skillet over medium-high heat. Melt 2 tbsp butter with 1 tbsp sesame oil in the skillet.

Add carrots, zucchini, and mushrooms to the skillet. Sauté for 10 to 12 minutes until softened.

Season the vegetables with salt and pepper. Transfer them to a plate.

Melt the remaining 2 tbsp butter and 1 tbsp sesame oil in the skillet. Add steak in a single layer, working in batches.

Toss the steak and cook each batch for no more than 3 to 4 minutes. Remove the skillet from the heat immediately.

Toss the hot steak with bbq sauce. Divide cooked rice, vegetables, and steak among four bowls.

Spoon yum yum sauce over each bowl. Finish with sesame seeds and serve immediately.

Remove the pan from the heat.

Toss the beef with the bbq sauce and plate the meal immediately with the cooked rice, veggies and beef, then top with yum yum sauce and sesame seeds.