This dish is delicious and versatile - don't eat beef? Use chicken, shrimp, or even try with firm tofu. Don't have carrots? Use julienned red pepper instead. I noticed in the comments section of the original recipe on New York Times Cooking that people used all sorts of vegetables with success. It was also in the comments that many people advised that the beef be tenderized through a process called 'velveting' - I decided to try it, and the texture of the beef was great. I included the instructions for that below.
Optional first step to tenderize meat: massage sliced beef with baking soda, cornstarch, water, and sugar. Allow to sit for at least 30 minutes.