Ready to get cooking? Follow these simple steps:

1. Start by marinating your steak. In a small bowl, mix olive oil, garlic powder, cumin, chili powder, salt, and pepper. Rub this mixture all over the flank steak and let it sit for at least 15 minutes, or up to 2 hours in the fridge.
2. Heat a grill pan or skillet over medium-high heat. Cook the steak for about 4-5 minutes on each side, or until it reaches your desired doneness. Let it rest for 5 minutes before slicing it thinly against the grain.
3. While the steak is resting, prepare your other ingredients. Heat the black beans and corn in a small saucepan over low heat, just until warmed through.
4. In a large bowl or individual bowls, layer the cooked rice, black beans, corn, cherry tomatoes, avocado, and sliced steak.
5. Sprinkle cilantro and cheese (if using) over the top, then drizzle with lime juice. Add a dollop of sour cream or Greek yogurt if desired.
6. Serve immediately and enjoy the vibrant flavors and textures!

Cooking tip: Use a meat thermometer to ensure your steak is cooked to perfection. It should read 135°F for medium-rare.