Mix the flour and salt in a bowl. Make a well in the middle, pour in the water, mix until you have a firm, elastic dough, knead on a lightly floured surface for approx. 5 mins. Shape the dough into a ball, return the dough to the bowl, cover and leave to rest until ready to use.
Cook the squash in salted water for approx. 20 mins. until soft, drain well. Using a blender, puree the squash with all the other ingredients up to and including the pepper. Cover and chill the filling until ready to use.
To shape and cook the ravioli
On a lightly floured surface, roll out the dough to approx. 2 mm thick. Cut out approx. 60 circles (each 10 cm in diameter), place on a sheet of baking paper dusted with flour. Spoon the filling into the middle of half of the circles. Brush the edges of the dough with a little water, cover the filled circles with the empty circles, press the edges down firmly. Cook the ravioli in salted water for approx. 3 mins. per batch, remove using a slotted spoon, drain well.
Heat the margarine in a wide frying pan, sauté the onions for approx. 3 mins. Add the sage, cook for 1 min., pour in the white wine, season, then bring to the boil. Add the ravioli to the sauce, heat for approx. 1 min., serve immediately.