Porrata Leek Pie
Strangely enough, the word "puree" seems to derive from the Italian word for leeks, porri. A soup made from porri was called a "porrea." At the annual festival held at San Lorenzo (of the famous Michelangelo sacristy), from the fourteenth century on, they served a passato, or puree, of leeks, and it appears that anything pureed gradually came to be called a "purea," which became "puree" in French and English.
Porrata is a large leek pie with a crust made of yeast dough. The leeks are sautéed in olive oil and butter and flavored with pancetta. This is even better cold than warm, and may be prepared in advance. A perfect antipasto to serve at a buffet or with before-dinner drinks, it is also suitable for a fancy occasion, and can serve a function similar to a quiche.
Rinse the leeks well, discard the green part, then slice them into rings 1/2 inch thick. Place the pieces in a large bowl of cold water for 30 minutes. Rinse several times to remove all grains of sand.
Heat the olive oil and butter in a large heavy casserole. When the butter is melted, add the leeks and sprinkle with salt and pepper. Cover the casserole and cook very slowly until the leeks are soft (30 to 40 minutes), stirring frequently with a wooden spoon. Remove the casserole from the heat and let the leeks stand until cold (about 1 hour). Meanwhile, make the crust.
Dissolve the yeast in the lukewarm or hot water.
Place the flour in a mound on a pasta board. Make a well in the flour, then pour in the dissolved yeast and add 2 eggs and salt. Mix with a wooden spoon, incorporating the flour from the inside rim of the well, little by little. When the dough is firm, start kneading. Knead until all but 2 tablespoons of flour is incorporated (about 20 minutes).
Sprinkle the dough with the remaining flour and cover it with a cotton dishtowel. Let stand in a warm place, away from drafts, until doubled in size (about 1-1/2 hours).
Chop the pancetta coarsely and set aside in a dish until needed; place the remaining 4 eggs in the casserole with the leeks and mix well with a wooden spoon.
Oil a 10-inch springform pan; preheat the oven to 400°F (205°C).
When the dough has risen, gently roll it, using a rolling pin, into a large sheet less than 1/2 inch thick. Fit the sheet of dough into the springform pan, letting the excess dough hang out over the edges.
Sprinkle the chopped pancetta over the dough, then, using a strainer-skimmer, fill the springform pan with the pureed leeks. With a knife, cut off the dough around the edges of the pan. Turn the edges inward, over the leeks, to make a border. Sprinkle with abundant freshly ground pepper (the dish should be peppery), then place the springform in the preheated oven for 45 to 50 minutes.
Remove the porrata from the oven and allow it to cool for 15 minutes before opening the springform. Remove from the springform and transfer to a serving dish. To serve, cut it like a pie. (The porrata may also be eaten cold.)