Defrost your frozen beef on the counter for 10-20 minutes until just soft enough to slice through with a knife, then carefully slice into very thin strips with a sharp knife.You can also use pre-sliced beef used for Korean bbq/fajitas etc. Peel and slice your ginger and garlic into thick slices, and prep your sauce by mixing all the ingredients in the list together until the sugar dissolves
Put a heavy pan on medium heat, and add in some oil when it’s hot
Add in your ginger, cook for a minute.
Add in your chilis and garlic and cook until the garlic starts browning, then scoop everything but the oil out of the pan into a bowl.
Turn the heat up to high. Add in your beef, keeping enough space between the pieces so that it doesn’t crowd the pan and give out too much water. Use tongs to separate the beef strips from eachother if needed.
Once the pieces start browning, lower the heat to medium and add in the onions. Fry for a couple minutes until they soften a little.
Then, add back in the chilis, ginger, and garlic. Pour in your sauce, and mix well.
Let it simmer for a minute until the oils come out again, Taste and adjust seasoning if needed, and take it off the heat.