Pat the steak dry using paper towels, season with salt, pepper, garlic powder, and onion powder, and let it rest for 15-20 minutes.

In a medium mixing bowl, combine sour cream or Greek yogurt, Dijon mustard, chopped herbs, garlic powder, salt, and pepper. Whisk until smooth, then refrigerate.

Preheat the grill over medium-high heat. Slice zucchini, coat with olive oil, salt, and pepper, and grill for 2-3 minutes on each side.

Grill the steak for 3-4 minutes on each side for medium-rare, using olive oil to prevent sticking and checking with a meat thermometer for doneness.

Let the steak rest on a cutting board for 5-10 minutes before slicing against the grain.

Assemble the bowl starting with rice or mashed potatoes, layered with zucchini and steak, and drizzle the creamy herb sauce on top.