I grew up in a VERY low sodium household, and still to this day, I maintain a lower sodium diet. Your friend will probably figure out how to eat in restaurants by learning what things to avoid. Also, when you go low sodium, your palate changes - it doesn't take long either. You start to get grossed out by oversalted foods. Your tastebuds grow more sensitive.
I tried to eat a green olive about three months ago. I spit it across the room, and washed my mouth out for two minutes. I still shudder just thinking about it.
ANYHOO -
You can be fine going to a restaurant, but as a general guideline for me, asian restaurants tend to be the saltiest. Especially americanized asian foods. Soy and oyster sauces are loaded with sodium. I've found also that generally, Polish restaurants overload on salt. Mexican and Italian are safe bets as long as you stay away from heavily sauced or "cheesed" dishes.
I would recommend for your first lunch you try for an Italian place.
Pasta with a grilled meat and sauteed spinach (and/or other veggies) tossed in an olive oil / lemon juice based sauce with no added salt in the prep. Any Italian joint worth it's
ahem *salt,* should be able to do this with VERY little interruption of the kitchen flow.
When (low sodium) eating in a restaurant, more things to consider
generally:
Gravy = bad
Sauce = bad
Foodservice Soup = VERY, VERY, VERY bad
cheese = bad
dips = bad
grilled meats = better
pasta = better (***olive oil based sauces are easy for chefs to modify/ create on the fly - don't expect marinara or alfredo to be altered for low sodium on request as it is more than likely pre-made )
Cured meats = VERY bad
Quick side note: tell your friend that unsalted butter mixed with lemon and balsamic vinegar is something to try as a sauce when getting tired of blandness from lower sodium eating. Also, sour cream is a cheap source of a salty flavor without the sodium.
We cannot be friends if you do not know the difference between Mayo and Miracle Whip.