Dissolve yeast in warm water, then add sugar and 250g of the flour. Mix and let rise about 1 hour.
Add remaining flour to the risen mixture, along with the eggs, butter, salt, milk and sultanas. Mix. Let rise again for 1 hour.
Heat oil in a large pan or wok. Drop dough by tablespoonfuls in hot oil and cook until brown on both sides. The fritter usually flips over when done on the first side. Be sure oil isn't too hot or your fritters may be raw inside when dark on the outside. Drain on kitchen paper. You may sprinkle with caster or icing sugar, if desired.
Called portzelky, these fritters are a traditional Mennonite New Year's treat. Use raisins or sultanas in this recipe.