Day 13 - What if I'm Vegetarian/Vegan?
CrossFit recommends a diet based in meats and vegetables as a starting point because meat contains complete proteins - i.e. proteins which contain adequate proportion of all nine of the essential amino acids necessary for the dietary needs of humans whereas incomplete (plant-based) proteins do not contain all of these amino acids. That isn't to say you can't get them without meat, it just becomes much more difficult.
If you are a vegetarian for moral reasons, do your research and look into supplementing things like branch chain amino acids (BCAAs) and the proper balance of protein and fats. If it's for health reasons, educate yourself and see if there are any animal types that are raised ethically that will be easier to help with your health and performance goals.
That being said - all of our plates should be overflowing with leafy green things. It would take you all day to eat 100 calories worth of spinach, so if you feel like snacking, be sure to start with a vegetable.
Further reading - https://www.boxrox.com/going-vegetarian-in-a-paleo-dominated-crossfit-world/