Ahead of time, you'll want to cook your rice. Rice typically triples in size when it cooks, so you'll need at least 1 ⅓ cups uncooked rice to start with. I typically make more just to have it on hand for the kids. You want the cooked rice to be cold when you make the pork fried rice, so if you need to chill it quickly, you can spread a thin layer on a cookie sheet and place in the refrigerator or even freezer.
Cut the pork tenderloin into very small pieces. This is easier if the meat is partially frozen and you use a serrated edge knife.
In a very large pan over medium heat, melt 1 T of the butter. Add the whisked egg and cook to a slightly underdone scramble. Transfer to a plate.
Increase heat under pan to medium high and melt another 1 T of butter. Add the tenderloin pieces, stirring only occasionally in order to get them to brown. Once mostly cooked, add the garlic, stir, and cook for a few more minutes. Transfer to a large plate.
Add another 1 T of butter to the pan. Saute the carrots, onion, and peas until slightly golden brown, stirring only occasionally. When done, transfer to the plate with the meat.
Add the remaining 2 T of butter to the pan. Add the cold rice and spread to an even layer. Allow to cook for a couple minutes before stirring to get the bottom layer to crisp up a bit. Then give it a good stir to heat through. Add meat and veggies back to the pan (along with any juices on the plate). Stir to combine to heat through. Add scrambled egg, green onions, soy sauce, sesame oil, and sesame seeds. Stir to combine. Add salt and pepper and additional soy sauce and/or sesame oil, if needed.