Mix together the marinade ingredients of olive oil, minced garlic, lemon juice, dried oregano, dried thyme, salt, and pepper in a bowl. Coat the sirloin steak thoroughly with this mixture and allow it to marinate in the refrigerator for at least 30 minutes up to 4 hours.
In another bowl, combine Greek yogurt (or coconut yogurt), grated cucumber (squeezed dry), lemon juice, minced garlic, chopped dill, and salt & pepper to taste. Mix well until all ingredients are smoothly integrated and place it in the fridge to chill while you prepare other components.
In a small bowl or jar, whisk together olive oil, fresh lemon juice, honey (if using), minced garlic, dried oregano, salt & pepper until well combined into an emulsified vinaigrette.
Heat a skillet over medium-high heat and sear the marinated steak for about 4-5 minutes per side until browned and cooked to your desired doneness. Remove from heat and let it rest briefly before slicing thinly against the grain.
Start layering your bowls by placing a base of cooked grains first and then top with sliced steak along with cherry tomatoes, diced cucumbers, sliced red onions, kalamata olives, roasted chickpeas (if using), feta cheese (if using), and fresh herbs.
Finally, drizzle each assembled bowl generously with chilled tzatziki sauce and vinaigrette dressing before serving immediately as a vibrant meal option!