The main difference between the peppers you find in the U.S. and the peppers you find in Italy is their nomenclature. For example, in America, "pepperoni" is the salami best known as a pizza topping, but in Italy, "peperoni" refers to large peppers. Both words are pronounced the same, but the English term has two p's. And peperoncini, which in the U.S. refers to the brined-pepper condiment, is any small variety of pepper in Italy. After you learn the classifications of peppers, you can easily find their counterparts in your local supermarket and incorporate them in your cooking just as the Italians do: according to personal taste.
Peperoncini aren't that side of pickled peppers supplied with your delivery pizza, even though those peppers, which are tasty in their own right, are small peppers, the literal translation of peperoncini. "Peperoncini" is a broad term; in Italian cooking, it refers to 85 varieties of peppers ranked according to their sweetness. To complicate things a bit, each region in Italy has its own name for peperoncini: In Calabria, if you want small peppers, ask for "diavulillo"; in Campania, ask for "peparuolo."
Diavoletti, or "little devils" -- the equivalent of small, hot red peppers, such as Thai chilis in the U.S. -- are commonly dried and ground for paprika and chili flakes, prepared fresh for inclusion in dishes or pickled for preservation.
Peperoncini verde, often one of the sweetest varieties, are similar to Anaheim chilis and candlelight peppers in America. Green peperoncini are commonly used fresh or pickled.
You find peperoncini in several colors, depending on the variety and stage of ripeness. There are also 1- to 2-inch long, multicolored peperoncini, collectively known as "peperoncini colorati," which are sweet and, although considered ornamental, completely edible.
Peperoni, another Anglicized term that denotes an entirely different food in Italy, describes the collective group of peppers known as bell peppers in the U.S. Translated as "big peppers," you can find two types of peperoni -- an elongated variety and a short variety; the short variety is the same as the majority of bell peppers in American supermarkets. This shorter variety is slightly sweeter than the longer variety, but that's about the only difference.
Like bells in America, peperoni color -- green, red, orange or yellow -- indicate the stage of ripeness. Also like bells, reds are sweet and fruity; oranges and yellows are mildly sweet; and greens have a touch of bitterness. Peperoni verde -- green bell peppers -- are the chief ingredient in the classic Italian dish peperonata.
Peperonata is a universal Italian-pepper condiment and side dish. Saute 1 part sliced onions and sliced bell peppers -- by weight; one pound of each makes about four servings -- in olive oil until softened, about 5 minutes. Next, add 1/2-part pureed tomatoes and season to taste with kosher salt and freshly ground black pepper. Simmer for an additional 15 minutes and finish with a touch of olive oil to smooth it all out.
Peperoncini al Mercato
Peperoncini al mercato are analogous to hot peppers in the U.S., and just as many varieties exist with just as much variance in capsicum content -- the chemical responsible for spiciness -- in Italy. Although peperoncini al mercato translates as "peppers at market," it always refers to hot peppers; common varieties include "lazzareto," "saverato," "friggitello" and "Jimmy Nardello."
Saverato -- from Calabria, the region commonly associated with chili peppers -- is a class of Italian hot peppers, and within the "saverato" class, numerous varieties of chilis with varying heat and color reside.
As in America, the uses for hot peppers are determined by taste and preference -- if you need a lazzareto for a spicy Italian dish, use a cayenne. If you need a sweet hot pepper, such as the "Jimmy Nardello," use Italian sweet peppers, as they're called in American markets. For "friggitello," a moderately spicy pepper, use a banana pepper or jalapeno.
Peperoncini al mercato are the main ingredient in bomba Calabrese, a hot sauce from Calabria similar to Serbian ajvar, French coulis and American roasted red pepper sauce.
Several versions of bomba Calabrese contain eggplants and artichokes, but in its simplest, purest form, you only need to focus on peppers: Roughly chop 2 parts each (by volume) of red onions, red bell pepper, serrano peppers, jalapenos and pickled peperoncinis. Mix in 1 part each scallions and garlic and cook in a few tablespoons of olive oil over low heat until softened, about 15 minutes; then season to taste with kosher salt and vinegar. You can use a food processor to roughly chop all the ingredients at once, if desired.