Dissolve the yeast in the warm water with a little sugar and leave it in a warm area to become effervescent. Mix half the flour with the remaining ingredients in a deep bowl. Add the ready yeast and stir with a wooden spoon.
Once homogenized, start adding the rest of the flour. If needed, add a little more flour than that listed - until you get a soft and slightly sticky dough.
Leave the dough in a warm area to rise for about 2 hours until doubled in volume. Roll out half the dough onto a floured counter into a sheet about 1/2″ (1 cm) thick and cut out circles using forms or a glass. Poke holes in their middles and leave them to rise again for about 40 min.
Then fry the donuts in generous amounts of heated oil (not too hot, so they can fry well on the inside as well). Sprinkle the ready donuts with powdered sugar.