In a shallow dish, whisk together olive oil, minced garlic, lime zest, lime juice, cumin, chili powder, salt, and pepper. Add the steak and massage the marinade into both sides. Let sit at room temperature for 15–20 minutes or refrigerate up to 2 hours.

Combine cilantro, Greek yogurt, mayonnaise (if using), lime juice, garlic, and salt in a blender or food processor. Blend until smooth, adding water 1 tablespoon at a time until pourable. Taste and adjust salt or lime as needed.

Preheat a grill or heavy skillet until very hot. Sear the steak 3–5 minutes per side for medium-rare depending on thickness. Use a meat thermometer for accuracy: 130–135°F (54–57°C) for medium-rare. Transfer to a cutting board and rest 5–10 minutes before slicing thinly across the grain.

Divide warm rice into four bowls. Top with sliced steak, cherry tomatoes, corn, avocado slices, and red onion. Drizzle with cilantro-lime sauce and garnish with cilantro leaves and lime wedges. Serve immediately.

Store components separately in airtight containers for up to 3–4 days. Reheat steak gently and add fresh avocado and sauce when serving for best texture.