Is there a word/phrase/idiom for temporarily satisfying strong feeling of hunger?

Imagine a situation where you've been invited to dinner at a friend's place. You're extremely hungry but you learn that the dinner won't be ready for another half an hour. So you decide to eat an apple or a bite of bread or some other small thing which will not satisfy your hunger fully, but will temporarily make it more tolerable. Is there a word/phrase/idiom to describe this small snack prior to a big meal?

The Russian equivalent of what I am looking for is заморить червячка, which literally means to starve/kill the little worm. The only translation I found of this idiom was to stay one's hunger. However, I couldn't find any usage examples of it and the google query for define:to stay one's hunger doesn't return anything useful, so I guess this idiom, if used at all, isn't very common.

To stay one's hunger is perfectly acceptable, and not at all uncommon (though it's actually more likely to be "stay your appetite"). Less common, and with less of a "temporarily" sense, would be assuage one's hunger. But I think probably the most common idiomatic usage is...

Here - have a sandwich to stave off your hunger until dinnertime.

...which my mother used to say to me when I was a child. Perhaps this one gains traction by alliteration / association with both stay and starve.

to stave off
to fend off, to ward off (something adverse) _{Merriam-Webster}

(To metaphorically repel / drive away using a stave = staff = stick.)

Although I see this has already been answered, I was surprised not to see 'tide you over' in the discussion.

After doing a little research, I see that this idiom is commonly used in situations like money lending: "I was flat broke, so he lent me $200 to tide me over until my next paycheck."

However, in my family we used it exclusively in situations like you described - and it was indeed often an apple I would eat to tide me over until dinner!