Thinly slice beef into approximately 1/2 inch, rectangular bite size pieces.
Boil these pieces with water and some salt.
Use enough water to cook the meat until tender (the water should dry up).
Do not add too much water or cook the meat too long.
While the meat is boiling, peel and cut the onions into cubes.
Cut chillies into half length wise and remove the seeds with the tip of a knife.
Handling the chillies with your hands can irritate your hands!
Make a paste of cornflour with 1 cup of water.
Heat oil and fry the beef pieces until slightly brown on medium heat.
Add onion and chillies, frying a little after each addition.
Add Chinese salt, ordinary salt, vinegar, soya sauce and the chicken stock/soup cooking for 2 minutes.
Before serving bring to boil, add cornflour paste very slowly, stirring to keep lumps from forming.
Cook for a minute on medium heat for few minutes.
Serve it with rice.