Bash the hell out of the rump (rolling pin or meat mallet - very cathartic) and cut into 1cm strips. Marinade with minced shallot, chilli, ginger, garlic and soy (only needs about an hour).
Drain off marinade and dredge in starch (potato flour is best, but cornflour works just as well). Dust it twice - the first time, the moisture will suck up the starch.
Get a wok smoking hot, add about an inch of oil. Stir fry beef for a couple of mins, then remove and drain on kitchen paper.
Make up a sticky s/s sauce with random cupboard stuff (honey or brown sugar, soy sauce, rice wine vinegar, rice wine, oyster sauce, splash of water) and thicken with a cornflour slurry.
Fry beef again and this time you can add in some of the veg (peppers, spring onions and green beans - or do these separately). You can then either throw in the sauce or serve it separately.