The plump ravioli called pansoti ("little bellies"), a Ligurian specialty, are often dressed with a walnut sauce. We strayed from tradition a bit and tucked the walnuts into the filling instead. Be sure to buy pancetta that's well marbled: If it's too lean, it won't render enough fat to flavor the filling. Also, brown the onions well — the caramelization lends a depth and richness that's essential to this dish.
· Pansoti can be formed (but not cooked) 1 day ahead. Arrange in 1 layer in a kitchen-towel-lined shallow baking pan and tightly cover with plastic wrap, then chill.
· If you don't have time to make fresh pasta, you can use wonton wrappers (thawed if frozen), but the flavor and texture won't be as good.
· Sauce can be made 1 day ahead and cooled, uncovered, then chilled, covered.
· Asparagus tips can be boiled and refreshed 1 day ahead and chilled in a sealed plastic bag along with a paper towel to absorb excess moisture. (Asparagus stalks can be used for a puréed soup.)
