Slice the beef against the grain into very thin slices (about 1/8” thick). It can help to put the beef in the freezer for an hour before cutting. This will not completely freeze the meat but will make it much easier to achieve a thin slice. Set meat aside.
Prepare the batter by combining the cornstarch, flour, white pepper, water, and egg into a large mixing bowl. Whisk the ingredients until there are no lumps.
Place the sliced beef into the batter mixture and allow it to marinate for 1 hour. If you have a lot of beef and you are having trouble getting the batter between all the pieces of meat you can add a little more water to discourage the meat from clumping together, you can add another ¼ cup or so if necessary.
While beef is marinating, prepare the sauce by combining soy sauce, sugar, water, rice vinegar, cooking wine, and crushed chili pepper flakes into a large bowl. Mix until well combined and sugar is dissolved. Set bowl aside.
Finely julienne the large carrot into 1-2” lengths. Cut up onion into 1-2” long, thin slices. Cut up bell peppers into 1-2” long, thin slices. Place the cut-up vegetables in a bowl and set aside.
Mince the garlic and ginger - set aside
Once the meat has finished marinating, pour oil into a large saucepan, wok, or Dutch oven to be at least 2-3” deep. Heat the oil to 350 F. It’s best to use a meat thermometer to know when the oil is hot enough, and to monitor the oil temperature periodically during cooking. The oil temperature drops dramatically once you begin deep frying. Try to keep the temperature at 350F during the whole cooking process.
When the oil has reached 350F, remove some of the beef slices from the marinating batter bowl and gently place in the hot oil. Work in batches so that the meat is not too crowded. Cook for 5-6 minutes or until the batter is a nice golden-dark brown. Use a slotted spoon to remove the meat to drain on a paper towel. Continue until all the beef has been cooked.
Heat a frypan on medium high heat. Add a tablespoon of vegetable oil and all the vegetables, garlic and ginger. Fry until tender, about 4-5 minutes.
Add the sauce to the fry pan and bring to a simmer. Continue cooking for 3 minutes to reduce a little bit. Add in the cooked beef and stir through so everything has been warmed up and coated in the sauce.
Serve over rice and enjoy. Garnish with sesame seeds and or green onions if you like.