To make these bowls, start by preparing the steak. Add the sirloin steak (or flank steak, if using) to a bowl or tray. Drizzle the olive oil and lime juice on top, then add in the chipotle peppers, mashed garlic, cumin, oregano, and ground black pepper.
Rub both sides of the steak well in the marinade mixture. Then, cover the bowl or tray and transfer the steak to the fridge. Allow it to marinate for a minimum of 30 minutes (or up to overnight).
While the steak is marinating, prepare the fajitas. Wash and slice the bell peppers, onions, and tomatoes, and set them aside.
Cook the rice according to your preferred method and set it aside.
Next, heat a cast iron skillet, on the stove, over medium-high heat, and add in the avocado oil.
Once the pan is hot, add in the steak -- be sure to wait until the pan is hot, otherwise the steak will turn grey and stick to the pan.
Allow the steak to cook for 4-5 minutes, undisturbed.
Then, flip the steak and allow it to cook for another 4-5 minutes, undisturbed. This is for a medium rare steak -- if you prefer a different cook on your steak (ex. medium well), you can leave it in the pan longer, until it reaches your desired doneness.
While the steak is cooking, prepare the guacamole (if making from scratch).
Once the steak is done, remove it from the pan and transfer it to a cutting board. Allow it to rest for 10 minutes before slicing.
While the steak is resting, cook the fajitas. Add the leftover marinade to the pan and toss in the chopped peppers and onions.
Sauté them for 3-5 minutes, until they've softened and cooked through.
Once the fajitas are done, remove them from the heat and assemble the bowls.
Add the rice to the bottom of the bowls, followed by the romaine lettuce, corn, black beans, baby tomatoes, and fajita vegetables.
Add the steak to the bowl, then add a generous scoop of guacamole on top.
Once the bowls are done, serve them immediately and enjoy!