I think one of the first things any expat misses is food. Like when you first move out of your childhood home and you start cooking for yourself, you miss your mom's home cooking. At least that's the first thing I noticed.
When I lived in New York City I had already become a vegetarian. I didn't eat anything that could walk the earth or swim in the seas. Just grains and legumes and fruit and vegetables. That kind of food can be found everywhere.
Yet, New York City offered me a wide variety of foodstuffs made from those basic ingredients. I shopped at a whole-foods cooperative that offered a range of things to eat that enriched my diet. I could buy tahini by the pound, freshly ground, just like the peanut butter. There was texturized soy protein, whole-grain bread and pasta, a plethora of nuts and seeds. They also sold "substitutes" for childhood favorites, like soy "hotdogs" and vegetable hamburgers.
My diet consisted of brown rice and vegetables, vegetables with vegetables, seed sauces and tofu shakes. I was in excellent health and never experienced any digestive problems. But then, I moved to Spain.
Gone were the affordable smooshed seeds. Tahini was nowhere to be found. Peanut butter was sold in tiny, expensive jars and only in that expensive supermarket, treated like caviar. I did have all the fruit and vegetables available at the local central market, but I was missing all those cute, vegetarian add-ons that had made my diet special.
At first I tried to substitute items, just as I had when I stopped eating meat. Instead of integral cookies I began eating cookies marketed as "home-made". Instead of texturized vegetable protein, I ate canned tuna and frozen hake fish. I did eat a lot of salads.
This transitional period of looking for substitutes led me to try buying food at a vitamin chain-store. This led to my most embarrassing false-friend experience with Spanish. I wanted strawberry jam without preservatives. So, I asked the lady in the shop if she had strawberry jam sin preservativos. She told me that none of their jams came con perservativos. What I really wanted was mermelada de fresas sin conservantes. Preservativos is the Spanish word for condoms.
On the same note, I remember a friend telling me that she was a little constipada. "That's too bad," I told her, "why don't you try eating a kiwi or an apple every day?" She, like the lady in the shop, didn't quite make a connection. We figured it out, constipada is a Spanish word that means having a head cold or a stuffy nose, not that more personal health issue involving a toilet....
Anyway, I later discovered the so-called "Mediterranean diet", a healthy combination of grains, vegetables, fresh fruit, fish and sea-food (and meats, but I still don't eat meat). I stopped trying to substitute those health products that I had depended upon in NYC. I began eating like the locals, choosing my ingredients wisely and not missing those that were simply not available.
Though I do mill my own peanut butter! Can't do without that!