Preheat oven to 350ºF/180ºC/gas 4. Line your baking tray with greaseproof paper. Set aside for later.
Season steak and set aside.
In a frying pan start by adding a little butter. Then add the stirfry vegetables. Add the soy sauce, oyster sauce, black pepper and salt. Then cover the pan and leave to soften.
Once the vegetables are done, remove them and place them in a bowl.
To start cooking the steak, heat up the pan by turning up the heat and leaving it there for 5 mins before adding any oil or butter.
After the pan is very hot, add your butter and place the steak in the pan. Cook for three minutes on each side whilst basting it regularly. Once done, remove from the heat and leave it to rest for five minutes. Then cut it into strips.
The last step is to cook your taco shells. Put them in the oven for three mins or until they turn a golden yellow colour.
Lastly, assemble all your components.
Notes
Vegan/ Vegetarian adaptation - Instead of using steak, you can use fried tofu. Do not use the oyster sauce, instead use a small amount of dark soy sauce