In a small bowl, make the sauce. Stir together the dark soy, soy, oyster sauce, and sesame oil, set aside.
In a large skillet over medium-high heat add 1/4 of the vegetable oil to the pan and add the beef, sear the steak, getting a char on it, cooking it until just done, 3-5 minutes. Place the beef on a plate and set aside.
Add ¼ of the vegetable oil to the skillet and saute the onion until softened and starting to brown, 2 minutes. Next, add the peas and carrots, until slightly softened for 3 minutes. Then add the cooked veggies to the plate with the beef.
Add ¼ more of the vegetable oil to the pan and scramble the egg, stirring occasionally until cooked, about 1 minute. Set aside on the plate with the beef and veggies.
Next, add the remaining vegetable oil to the pan and add the rice. Let it sit for about 2 minutes to get a slight char, stir it around.
Add the cooked beef, veggies, and egg back to the pan, stir to combine.
Lastly, add the sauce and stir to coat everything. Continue to cook for about 3 more minutes so everything warms through and the flavors can blend.
Serve immediately with a garnish of sliced green onions (optional).
Notes
Switch out the meat if you like or just make vegetable fried rice. you could even use cooked ground beef.
This can be frozen, see my tips above.
You can use any cooked rice that you'd like.
Dark soy sauce can be replaced by regular soy sauce.
If you don't like sesame oil, just leave out.
Oyster sauce is optional but it adds a wonderful depth of flavor and is often used in many Asian dishes.