Honestly stir fry and fried rice are incredibly simple. You can use just about any sort of ingredients/flavoring you want and it still works.

I'm not a great direction-giver because I don't measure when I cook or follow strict formulas, and I season everything to taste but I'll give you the best rundown I can on my basics;

Stir fry: Cook vegetables in sauce, remove vegetables, cook meat, re-add vegetables. It's that easy. When using the crispy beef like this recipe that is already cooked, I add/toss it right before serving so it doesn't get soggy.

Fried rice: Use day-old rice (better texture). I like to cook everything separately; I cook a scrambled egg and set it aside, then I do the meat (in this case, oven bacon on foil that I chop up at the end), set it aside. Then I add oil, or in this case a bit of bacon grease, while I fry my garlic/onions and add in vegetables. Then I add everything else (rice/meat/egg) back in and cook it on high heat while adding soy sauce until it tastes good, stirring constantly to break up the rice and mix everything well.

Pertaining to this particular recipe;

Always dry your steak off before corn starching it. Roll the steak strips heavily in the corn starch (you can season the cornstarch if you want, salt/pepper/chile/whatever) and let it sit 10-15 minuted before you fry it or the corn starch doesn't stick and comes off in the oil (sometimes you may want to do a second coating if it all absorbs into the steak). Put some oil in a pan on high heat and fry them until the outside is crispy.

For my sauce I start with simmering soysauce in a pot, add some light ginger, chile paste, cayenne, a good squeeze of honey, and a little rice vinegar. You can add cornstarch to thicken it up as much as you want, but add small amounts and watch it for a minute because it takes a second to thicken up when it's cooking and it's easy to over-thicken it.

/ramble