I like coffee and I live in Russia which is not generally a coffee drinking country.
More often than not, when you ask for an espresso in Russia, you get 100 to 150 ml of liquid in your cup.
The cafes as a rule have the good equipment: espresso machines, grinders etc., but for some reason the Russian barista's idea of an espresso is usually take a big cup and wait for the machine to fill it all the way up. Sometimes you get a warning "you know an espresso is a very small cup of coffee, right?", which is a good sign.
I assume most people who are not familiar with espresso feel cheated when they get hardly enough liquid to cover the bottom of the cup, so the baristas and the cafe owners have to account for it.
At one place I had to ask to have my coffee re-made, and the response from the lady at the counter was "wow, finally someone who knows how to drink the right kind of coffee". But this is the exception rather than the rule, and most often you get pursed lips and avoided eye contact.
There are places which know how to make their coffee, and I'm familiar with all of them which are next to the place where I live. However when I'm eating out and want to finish my dinner with a nice cup of coffee, or when I'm away from home, I'm at the mercy of the person operating the machine this day.
I feel awkward when I come to the place I've never been before and try to tell the barista how to do their job. However, if I'm not specific enough, like in "I want this cup to be filled this high, and I want it to take this long", there is a good chance I get a full cup of watery and bitter swill from a good-meaning person. And it's twice as hard when you have to communicate it through the waiter or the cashier rather than talk to the barista themselves.
I have no problem being Ron Swanson ordering bacon and eggs if I know I have to, but there's always a chance the barista actually knows their job.
Question: how do I communicate that I'm ordering one sip of coffee and I mean it, without offending the barista?
Update: you totally have to be really really specific and use absolute units of measure if you want your coffee made the way they make it in Italy.
I'm speaking from experience. 4 times out of 5 if I'm not being that specific, I get my coffee severely over-extracted.
Russia is a tea drinking country, words like "small cup" don't really translate from tea to coffee. 100 ml is a very small cup of tea but a very large cup of espresso.
And the real problem is that the staff rarely if ever get complaints about being served too much coffee but get many about being served too little. If you don't assure them they won't get in any trouble by serving you two tablespoons of coffee, they'll pour you more, just to be on the safe side.
The best course of action is take the cup, mark the level with your nail and say "could you please set the grind level one step finer than you usually do and fill the cup up to this mark here?"
As I said before, I have no problem doing that if I know I really have to (say the second time I visit the place), but it's awkward to start the first conversation with a barista by making an assumption they don't know how to do their job.
The question is how to avoid accidentally alienating the 20% of baristas who know what they are doing, given that the other 80% need the very specific instructions.