Inspired in part by the Romano/America comics on tumblr by Moriar-Tea, and also just my personal headcanon for these two. I don't own either of them.
Romano could practically count this game he and America shared as a tradition now after so many years. Whenever he went to visit America, at least once the blonde wanted him to try something "inspired by Italian food" and not like what he'd had before. Sometimes it was pizza, sometimes it was macaroni with the powder the other liked to swear up and down was real cheese and was incredibly tasty. Other times, it was restaurants that served their pasta with so much sauce and cheese that the noodles couldn't even be tasted, with the sauce containing very few spices and with the noodles by themselves bleached out and bland. Romano liked tomatoes, but he wanted to taste more than tomatoes and cheese. Olive Garden was a disaster every time he went – there wasn't even ever any wine beyond the label of "decent" (though Romano could admit he was a bit biased) to make up for it! It was best not to even get him started on the coffee that America tried to make, instant or otherwise. The stuff America tried to call a latte or a macchiato was downright awful.
However, the South Italian was well-aware of the game America played. It was all for the other to be able to watch him get fired up over food, and Romano could see the glint of amusement in America's eyes and the smile playing at the other's lips with each failed effort to get him to like something where the blonde's citizens had tried to mimic his food. In addition, it was all too easy to get Romano muttering curses into his food – if he said nothing at first, all the other nation had to do was insist the version his citizens made was somehow better, and the Italian's temper would flare.
It was generally worth it to Romano to play this game, though. After America had gotten his fill of Romano ranting and pouting about how the other's imitation Italian food was too fried, too greasy or altogether tasteless and in no way worthy of a stamp of approval from him, the dark auburn haired nation would generally get what he wanted somehow. Sometimes he'd end up cooking America dinner himself, and sometimes after several hours of being in the kitchen, he could swell with pride when the other finally gave in to agreeing that his version was superior. Other times, when Romano was feeling too lazy to cook, America would take him to some hole-in-the-wall place run by first generation Italian immigrants, where Romano could both enjoy eating something authentically made of fairly good quality and chat up those who ran the restaurant in his own language. This was the only reason he bothered humoring America at all with such a game. Besides, he knew America liked seeing him proud and happy just as much as the blonde (strangely) enjoyed seeing him try not to gag at efforts to impress him with cheap "Italian" food, and to be the cause of America's smile was well worth the risk of putting something awful-tasting in his mouth. If America's food gave him indigestion… that generally meant all the more pampering for him, anyways.