Here’s the way Angelina made it: You saute a goodly amount of chopped onion–with a little chopped parsley if you like–in olive oil, seasoning with a salt and generous amount of pepper. Let it go, adding a tablespoon or so of water from time to time to soften the onions and avoid their browning, until they are quite soft and their sweetness has developed nicely. Then add a can of peas with its juice. (NB: This is the only time I ever use the juice from a canned product.) Let it simmer gently, just long enough to heat the peas. Separately, boil ditali or another small, stubby pasta (see below) in well salted water and then add to the peas. Allow them to simmer together for just a minute, adding a bit of pasta water if the pasta is too dry for your taste (see below) then leave off heat, covered, for two minutes or so, to allow the flavors to meld. Serve with additional freshly ground pepper, if you like, and un filo d’olio. Et voila!
NOTES: The above is the quick and easy method. For a dish that is more genuino as they say in Italian, use fresh peas. You add the shelled peas to the onion soffritto, saute for a minute or two to allow the peas to absorb the flavor, then add enough broth or water just to cover the peas. Simmer until the peas are tender and proceed as indicated in the main recipe. You can also use frozen peas in the same way, which are convenient but greener and sweeter than the canned variety.
Some variations. The foregoing recipe is the one I grew up with in an Italian-American family. In Italy, it is more common to use either fresh or frozen peas, to which either broth or water is added, rather than canned peas and their canning liquid.
The dish I grew up with had no meat and no tomato–in bianco as they say in Italian. But a lot of people add bits of pancetta (Italian bacon) or cooked ham to saute along with the onions. And some people also like to add a bit of tomato after the onion and/or pancetta and/or parsley have sauteed, for a bit more color and taste. Allow the tomato to reduce before adding your peas, and proceed as indicated in the main recipe. I have also seen recipes calling for you to use shallot (scalogno) instead of onion. You can also vary the amount of onion. I use lots of onion–a whole smallish onion for two people–which adds considerable sweetness. If you are using really fresh, young, sweet peas, you may need less onion. (I have also seen recipes calling for the addition of a pinch of sugar to add sweetness, but personally the idea does not attract me.) Finally, some people like their pasta e piselli dry (in which case, leave out the liquid or use much less). I grew up with a rather wet pasta, almost a soup, and I like it that way. (This is one pasta, btw, that you are better off eating with a spoon.) Some people, in fact, like to squash some of the peas against the side of the pan as they cook, to thicken the broth and make it creamier. And I always ate my pasta e piselli with lots of freshly ground pepper–I really like the contrast between the sweetness of the onion and peas and the spiciness of the pepper–but this is not necessary if you don’t care for pepper. I’ve seen recipes calling for a dusting of parmesan cheese as well, but this stikes me a slightly sacrilegious.
The choice of pasta is important here. The original and–to my taste–by far the best choice are a very small tubular pasta called ditali, ditalini or tubetti. (NB: This is one of the many examples of basically the same shape of pasta having multiple names according to region.) Also a very good choice are the tiny shell-shape pasta called chioccioline or conchigliette which some say is even better because they concave surface catches the peas. Some people even use spaghetti or linguine broken up into short lengths. (That’s how my grandmother made pasta e lenticchie, but never this dish.) Why not experiment with different pastas to see which one you like best. As they say, “variety is the spice of life.”