Remove and discard any visible fat from the beef and cut the beef into strips. Place in a bowl with the plum sauce and lime zest and juice and leave to marinate for 30 minutes.
Heat a non-stick wok and dry-fry the onion, garlic and for 3/4 minutes over a high heat, seasoning with black pepper. Add the marinated beef and the mushrooms and continue cooking for 2/3 minutes.
Add the remaining ingredients, except the peas, and toss well together, making sure all the pieces of beef are sealed. Just before serving, stir in the peas.
Serve straight away with additional stir-fry vegetables and some plum sauce on the side.