You sauté 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 the peas simmer gently, just long enough to heat the peas.
Separately, boil ditali or another small, stubby pasta (see Notes 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, 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!