Combine flour, milk, egg, margarine and salt. Beat with an egg beater until a smooth batter forms.
Slice onions horizontally to make rings.
Dip onion rings into batter, and drain away excess batter.
Heat adequate amount of oil in wok or frying pan, and put in onion rings and fry until golden brown in colour. Take out and drain excess oil. Sprinkle some salt and pepper and serve.
Choose yellow onions for sweeter, juicier onino rings.
When frying onion rings, use a fork to gently turn them over. Do not fry too many at one time, as they will stick together.