When friends come over for dinner, Jackie and I like to serve a small first course that's elegant and a little surprising. That's not to say it needs to be complicated: A thick slice of celery root braised in butter and served on its own (with or without sauce) is a good example.
Filled pasta takes quite a bit more work, but it meets our criteria in spades: a few pretty bundles of egg pasta are inherently elegant in appearance, and an unexpected filling provides the surprise (a pleasant one, with any luck). I devised the most recent version in two stages: There are delicious leeks in our local farmers' markets, and I'd decided they'd be the main ingredient of the filling; beyond that, I wasn't sure. Ricotta, perhaps? Some sort of cheese? Even a simple chicken mousse, used as a binder, seemed like a possibility. Then - as often happens - something we ate in a restaurant provided the answer: A spectacular dish of turbot with creamed leeks and an airy lemon sauce, eaten at New York's Jean-Georges. The tart, aromatic lemon worked together with the sweetness, onioniness and mild savoriness of the leeks in an almost startling way. It wasn't just the lemon flavor, it was the liberal hand with which it had been dispensed.
So that became the flavor plan for my ravioli filling. (Or agnolotti. Or tortelli. These terms are so loose and mean different things in different regions. I think I'll call these agnolotti.)
The day before making them, I began by gently sweating the white and palest green parts of three large leeks, well washed and finely chopped, in plenty of butter, with salt. To wash them, I'd cut them in quarters lengthwise, but not all the way to the root end, creating a sort of brush that could be whisked vigorously in cold water; I left them in a strainer to drain before chopping them. When the leeks were tender, I raised the heat to medium-high and added half a cup (120 ml) of white wine, which I reduced until it stopped smelling alcoholic. Then, with the heat reduced to medium-low, in went half a cup of crème fraîche and about a quarter cup of heavy cream (3/4 cup of either by itself would have been okay too) to reduce and thicken: the idea was for the cream to lightly bind the tender leeks. The mixture needed to be moist, but not runny.
When it was thoroughly cool, I stirred in the grated zest of three - yes, three - good-sized lemons and a couple of slivered leaves of sage (parsley would have been nice too) then tasted the mixture. It needed salt, and it needed something more in the lemon line - just a bare tablespoon of lemon juice - before being stowed in the fridge to firm up overnight (a few hours would have been sufficient).
For this amount of filling, I made pasta with 250 grams (a little more than half a pound - a scant two cups) of flour, one whole egg and three yolks, plus a little extra white as needed, let it rest, then rolled it out on my old hand-cranked machine to the second-thinnest setting. To form the agnolotti, I used my current favorite wrap: that of ravioli del plin, which you can see on a YouTube video (the soundtrack is in Italian, but the demonstration is admirably clear), though mine were larger than the ones in the video. With many mixtures, I use a pastry bag to deposit (more or less) equal blobs of filling on the pasta sheet, but with very stiff ones (like the ground meat-and-cheese blend used for tortellini) and with particularly moist ones (like this one), I use a spoon and/or my fingers to make little balls and place these on a tray before setting them onto the pasta. Squeezing this leek mixture through a bag would press liquid out and create puddles on the dough, which could erode the thin pasta.
I wasn't planning to use these immediately, and I was making enough for a subsequent meal for Jackie and me, so as I formed them I put them on a paper-lined tray in the freezer, then transferred them to a plastic bag when they'd hardened. I dropped them into slowly boiling salted water directly from the freezer; when the water returned to the boil, I kept it at a high simmer for gentle cooking. This took five or six minutes.
For a typical dinner-party starter, a portion might be five of these plump agnolotti (for a main course, perhaps a dozen); that evening I served only four because some guests were exercising post-holiday prudence - and in any event there was a big meaty main course to come. (If anyone had complained, it would have taken only a few minutes to boil some more right out of the freezer.) I dressed them just with butter and a few grains of salt: no cheese.
Their flavor had all the leek-and-lemon virtues described earlier, and the uncommonly moist filling made cutting into them (with a spoon) a happy moment as the creamy, citrusy mixture flowed out - not quite like eating Shanghai-style soup dumplings, but along those lines.
Elegant? Check. Pleasantly surprising? Check. So, they were a success.