Pat the steak dry with paper towels, season generously, and let rest at room temperature for 15-20 minutes.

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

Slice zucchini into 1/2-inch rounds, toss with olive oil, salt, and pepper. Grill for 2-3 minutes on each side.

Cook the seasoned steak on a preheated grill for 3-4 minutes on each side until medium-rare, rest for 5-10 minutes.

Assemble bowls with a base of rice or mashed potatoes, top with grilled zucchini and sliced steak, drizzle with herb sauce.