Slice the top round into strips 1 inch x 0.25 inch x 0.25 inch. Do this by cutting against the bias of the grain to ensure that this inexpensive cut of beef will fall apart when eaten.

Mix beef with corn starch, soy sauce, and black pepper in a bowl and set aside.

Slice onions into strips.

Fry beef in a large pan until golden brown and caramelized on high. Do not crowd the pan -- this is a fry not a boil.

Throw onions into pan and saute until desired textured.