Whisk the marinade ingredients -- coconut aminos, lime juice, chili powder, cumin, salt, and garlic -- together in a small bowl.
Place the steak into a large plastic bag, then pour the marinade overtop. Seal the bag, then press the marinade around so that the steak is coated. Place the bag in the refrigerator for at least 30 minutes, or up to 8 hours.
Once you're ready to eat, heat a large cast iron skillet over medium-high heat, then use kitchen tongs to grab the steak from the plastic bag and place it directly onto the skillet (discard any remaining marinade, or save it for another use). Cook the steak for 4 minutes per side (or longer, depending on how you like your steak), then transfer it to a cutting board. Let it sit for a few minutes before slicing.
Next, pour the chicken broth into the skillet. using a wooden spoon to scrape up any brown bits. Then, add the bell peppers and red onion to the skillet, reducing the heat to medium and cooking for 5-8 minutes, or until soft.
While the peppers are cooking, make the cilantro lime cauliflower rice. Microwave the cauliflower rice according to the package instructions (or heat in a skillet). Once it's cooked, pour it into a bowl and add the lime juice, cilantro, salt and pepper; stir to combine. At this point, you should also prep the guacamole if using: mash the avocados in a bowl, then add the lime juice, cilantro, salt, and pepper and continue mashing until it's at your desired consistency.
Last, assemble the bowls: Distribute the cauliflower rice into bowls, then distribute the cooked peppers/onion. Slice the steak into thin strips, then add it to the bowls. Add any optional toppings and enjoy!