Roughly chop the onion and pepper to about 1-inch pieces. Cut your beef into thin slices that are about 2 inches in size.
Add the beef, baking soda, and ¼ cup of water to a large bowl. Mix everything well and let the meat tenderize for 15 minutes. Then rinse your meat until it no longer feels slippery and you remove the baking soda.
Season the beef by adding salt, sugar, black pepper, chicken bouillon, cooking wine, sesame oil, MSG, water, and cornstarch. Add 2 cups of oil to a big pan over medium-high heat. Fry the beef for 3 minutes. Make sure to stir while frying because the meat tends to stick together. You might have to fry in 2 batches depending on how big your pan is.
Add 1 tablespoon of oil to a Chinese wok or a big pan over medium-high heat and saute the onion and peppers for 1 minute. Then mix 1 tablespoon of cornstarch into the soy sauce. Add the soy sauce mixture, water, garlic, and beef to the pan. Cook for 6 minutes so the sauce can thicken. Enjoy!
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Notes
Make sure to cut the meat finely. This helps it soften better and to cook very quickly.
When tenderizing the meat, do not leave it in the baking soda for too long. If you leave it for too long it will become chewy and have a strong metallic taste.
If you don't have white wine vinegar, just use half of distilled white vinegar