In a small skillet cook the shallot in the butter over moderately low heat, stirring, until it is soft, transfer the mixture to a bowl, and let it cool.
Stir in the salmon, cream cheese, dill, chives, lemon juice, and salt and pepper to taste.
Stir until the filling is throughly mixed and chill the filling, covered, until well-chilled.
Put 1 won ton wrapper on a lightly floured surface, add 1 tablespoon of the filling in the center,brush the edges well, trim the excess dough around the filling.
Repeat with remainder of wrappers, then transfer to a dry kitchen towel, turning occasionally to let them dry slightly.
Bring a pot of boiling salted water to a gentle boil and in it cook the ravioli in batches for 2 minutes, or until they rise to the surface and are tender.
(Do not let the water boil vigorously once the ravioli have been added.) Transfer the ravioli as they are cooked with a slotted spoon to a dry kitchen towel or paper towels to drain and keep them warm.
Arrange 3 of them on each of 4 heated plates.
Drizzle the ravioli with the melted butter and serve them with the sour cream and dill.