Ravioli is an Italian pasta shaped like squares or circles and stuffed with fillings before cooking. Most are familiar with meat raviolis, but there are unlimited versions of ravioli, including vegetarian kinds such as pumpkin ravioli. It is a food with a long history that started before ravioli pasta machines were available. Raviolis made by hand are still delicious and easy to do.
Place 3 cups of flour in a mixing bowl. Add 4 eggs and 1 tsp. of salt to the flour. Mix it all together. This can be done by hand or by an electric mixer with a dough hook. Add the oil a little at a time and keep mixing until you have a ball of dough. Turn the ball of dough onto a floured surface. Cover with a mixing bowl and allow the dough to rest for about 20 minutes.
Divide the dough in half and set aside half for a few minutes. Roll out the first half on the floured surface with a rolling pin. The dough will be sticky so sprinkle with a little flour as you go when it sticks to the rolling pin. Roll the dough until it is paper thin.
Cut circles or squares from the dough with a ravioli cutter. Lay the circles or squares aside. Continue until all the dough is used. Throw cutting scraps into the second half of dough while working on the first half. Knead the scraps and second half of the pasta dough together and repeat the rolling and cutting process with it.
Stir one egg yolk in a small bowl. Take approximately 1 tsp. of filling and place it on top of one cut ravioli in the center so that there is still and edge of dough surrounding the filling. Brush this dough edge with the egg yolk. Place another cut ravioli on top of the piece with filling. Crimp the edges together all the way around the ravioli sealing the filling inside. The egg yolk acts as a glue to help hold them together. Continue process until all raviolis are made. Cook by the desired method.