Pat the steak dry with paper towels and season with salt, pepper, garlic powder, and onion powder. Let rest at room temperature for 15-20 minutes.

In a bowl, whisk together sour cream or Greek yogurt, Dijon mustard, fresh herbs, garlic powder, salt, and pepper until smooth. Refrigerate for at least 10 minutes.

Slice zucchini, toss with olive oil, salt, and pepper. Grill for 2-3 minutes on each side until softened and charred.

Preheat a grill pan with olive oil, then cook the seasoned steak for 3-4 minutes on each side for medium-rare. Let rest for 5-10 minutes.

Assemble the bowl with a base of rice or mashed potatoes, topped with grilled zucchini and sliced steak. Drizzle with herb sauce.