Using a food processor, blender or sharp knife, pulse head of cauliflower into rice size pieces. (or save yourself a step and buy some cauliflower already riced. It seems to be everywhere these days.)
In a medium to large sauce pan (depending how much you are making), heat oil over medium heat and slowly stir in cauliflower rice. Stir for 2-3 minutes.
Add in diced onion, diced bell pepper and salsa and stir until well combined.
Bring rice mixture to a low rolling boil, stirring every minute or so until boiling. Reduce heat to low/simmer, cover pot with a lid and let rest for 20 minutes. You may stir 1 time while pot is simmering, but leave covered. The liquid may not cover the whole batch, but it will still be cooking evenly.
Serve as a side dish with your meal and store any leftovers to heat up for a future meal!