Beat the steak slices until very thin. Mix the ginger and soy sauce in a bowl, add the meat and leave to marinate for 30 minutes, turning occasionally.
Lightly beat the egg whites then beat in the cornstarch to make a smooth batter.
Heat the oil to 180°C/350°F. Dip the beef slices into the batter, then deep-fry a few slices at a time until golden brown Drain on absorbent kitchen paper. Transfer to a plate and garnish with the shredded scallions.
Serve hot with a selection of dips, such as soy sauce with grated garlic, hoisin sauce and tomato ketchup (sauce).