In a frying pan on medium heat, add the coconut oil, and once warm, add the coconut slivers. Mix frequently, as these can overcook very quickly.
As soon as the coconut pieces start to turn golden on the edges, add the chopped pearl onions, chopped garlic and ginger, green chilies, and a pinch of salt.
Cook until the pearl onions turn golden and the ginger and garlic are cooked.
Next, add the cooked beef and all its masala to the pan and mix well. As the beef should have almost no gravy, add a cup of water to it and mix well.
This step may be the longest hands-on one. Keep the pan on medium high heat, and mix the curry well. The water will start to evaporate, the gravy will thicken and the curry will turn darker. This is the part where you roast the beef Ularthiyathu, and the whole dish will turn a warm red brown color.
Once the curry is semi-dry [it will take about 10 minutes], add the black pepper, vinegar and curry leaves to the pan. Mix well and cook for a further 2-3 minutes, stirring frequently.
Lastly, once you are happy with the consistency of the gravy [keep it semi-dry or more liquid for a main course, and dry for a starter], add a last teaspoon of coconut oil, mix well and the Kerala beef fry is ready to be served with rice, parottas, appam, or any type of flat bread you like!