01 - Preheat grill or grill pan over medium-high heat. Pat steak dry and season both sides with salt, black pepper, and garlic powder. Brush both steak and sliced zucchini with olive oil, then season zucchini with salt and black pepper.
02 - Place zucchini on the grill and cook for 2 to 3 minutes per side until charred and tender; set aside. Grill steak for 4 to 5 minutes per side for medium doneness. Transfer steak to a plate, tent with foil, and let rest for at least 5 minutes before slicing against the grain.
03 - In a mixing bowl, whisk together Greek yogurt or sour cream, Dijon mustard, minced garlic, lemon juice, salt, and black pepper until smooth. Adjust seasoning to taste.
04 - Arrange cooked rice, quinoa, or salad greens as the base in each bowl. Top with sliced steak, grilled zucchini, and halved cherry tomatoes. Drizzle creamy sauce over ingredients and sprinkle with crumbled feta or Parmesan cheese if desired.