Place the steak in a bowl and add the soy sauce and egg. Mix together well then set aside.
Fry the onion and garlic in a large pan until fragrant. Add the soy sauce, honey, Hoisin or Oyster sauce, vinegar and water.
Bring to a simmer and allow to reduce by half. Remove from the heat and set aside.
Heat enough oil to deep fry the beef in a pot set over high heat.
Dip the steak strips into the flour, making sure each strip is well-coated. Shake off the excess then add to the hot oil, frying the beef in batches until golden brown and crisp.
Remove with a slotted spoon and allow to drain on kitchen towel.
Place the sauce back on the heat then add the beef and toss well to coat the meat in the sauce. Add cooked noodles and season with more soy sauce, honey or vinegar if needed.
Serve in a bowl and sprinkle with thinly sliced spring onions and sesame.