Cut your fish cakes into bite sized pieces if they are large. You can use any kind you prefer- sheets, fish balls, etc.
Add some oil to a pan on medium heat and stir fry the onions and fish cakes for about 1 minute.
Add the sauce to the pan, but reserve about 1 tablespoon of the sauce to use for your dosirak (optional).
Stir fry for 2-3 minutes but be careful not to burn. Lower the heat if needed.
Pack your lunchbox with the fish cakes, rice, and whatever banchan you have. I am using kimchi, seasoned spinach, seasoned bean sprouts, and stir fried anchovies (recipe soon).
Top the rice with the reserved sauce from the fish cakes, some seasoned seaweed, and a fried egg.
Shake the dosirak vigorously to make bibimbap or you can just enjoy as is.