To some degree, American Food is a style of food preparation originating in the New World. European colonization of the Americas yielded the introduction of a number of ingredients and cooking styles to the latter. The various styles continued expanding well in to the 19th and 20th centuries, proportional to the influx of immigrants from many foreign nations; such influx developed a rich diversity in food preparation throughout the country. This being said, "American Food" just like "American People" can be considered to be a variety or combination of foods from other countries modified to suit the palate of the general public. The recipes can and do vary between the different regions of the United States and in some cases can vary within a particular state such as Texas where "Mexican Style" or "Tex Mex" can be quite different in Houston when compared to Dallas / Fort Worth.
So, are there any foods that really are 'all American?' By all American, we mean those which originated in the USA and are now part of the entire world's diet. You may be surprised to learn that not only is there a large number of them, but that many are also becoming world dietary staples. Chocolate and vanilla, both originated on the North American continent, and you can add peanuts, pineapples and tapioca with those sweets as well.
And maize or corn, (whether sweet corn or field corn) has become staple for both animals and humans in many areas, and then there is the movie industry - where they would be a different scene without hot, fresh popcorn.
Then there is the lowly bean. Beans are even mentioned in biblical times but there were no true beans anywhere in the 'Old World' during those years. The Old World had chickpeas, lentils and fava beans. But, none of these are true beans, they are all vetches (peas). The haricot bean, a wide ranging family that includes runner beans, kidney beans, pinto beans, butter beans, navy beans, great northerns and lima beans are all New World plants. You can add sweet and hot peppers now consumed around the world as American too.
The New World Turkey made it to Europe around 1523 or 1524 and then England shortly there after, closely followed by the white potato, which reached England later that century.
Just to round things out a bit, throw in allspice, amaranth, artichoke, avocado, blackberry, blueberry, cashew nut, black cherry, cranberry, concord grape, guava, huckleberry, papaya, pecan, pumpkin, squash, raspberry, wild rice, sassafras, sunflower, sweet potato, and the tomato.
Now, those are real 'all American foods.' Bean soup and corn bread along with fresh sliced tomatoes anyone? It is as American as apple pie. Anyone up for a chocolate bar?