Well I grow up in Hong Kong and I know about the Northern
Chinese/Taiwanese you-tiao + siu-bang (salty cakes) + soy milk
breakfast. (Maybe because my mom lived in Shanghai for a while.) It
can be served with plain, sweet, or savoury (with pickles and chili
oil) soy milk, you would dip the you-tiao into the soy milk before
biting into it. The method with the siu-bang is (to me) a little
strange, you open up the flat crispy cake and stuff the you-tiao into
it, making a kind of sandwich, which you then dip and eat.

Cruller is a name for a fried cake, and here in North American a kind
of doughnut (donut) so it's sweet. So I wouldn't call you-taio
"mandarin for crullers".