Put a cooking pan on medium to high heat and heat the oil.
Once the oil is heated, add the hotdogs and cook them for 3-4 minutes or until they're browned. After the hotdogs are cooked, take them out of the pan and set them aside.
Using the same cooking pan, add the onions and garlic then saute them until the vegetables are limp and aromatic.
Pour in the banana ketchup, vinegar, oyster sauce, and sugar then add the water and season with salt and pepper. Make sure to stir everything together and bring the mixture to a boil.
When the sauce reaches a boil, add the hotdogs into the mix and cook everything until the sauce is reduced and thickened. To avoid the sauce sticking to the pan, make sure to stir the mixture occasionally.
After bringing the mixture to a boil, transfer the stir fry to a plate and enjoy.