1To make the tomato sauce:
2Bring a medium size pot of water to a boil. Add the plum tomatoes for 1 min. Transfer them to a cutting board and let cool. Once ready to handle peel off the skin. Grate the tomatoes with stainless steel box grater using the largest grain.
3Heat 1 tablespoon olive oil in a large saucepan over medium heat. Stir in the diced onions and garlic, season with 1 teaspoon kosher salt and cook until translucent for 4-5 minutes, and add the grated tomatoes.
4Lower the heat to simmer and cook it for 1 hour, while occasionally stirring the mixture, so it doesn’t stick to the bottom of the pan, until the sauce thicken slightly.
5To make the ravioli:
6Lay one pasta sheet on a lightly dusted working surface. With the ravioli shapecutter mark each piece by lightly pressing the form onto the dough by leaving at least 1/2” between each shape. Once you have you pieces marked, brush the contours with a whisked egg. Place half tablespoon of the walnut-ricotta filling. Line up with the second dough sheet and firmly press with the ravioli cutter. Remove the extra dough, lightly dust with flour the ravioli and transfer them to a clean tray.
7To make the filling:
8In a mortar gently crush the walnuts until almost smooth texture.
9Transfer the mixture to a boil and combine it with the ricotta and pinch of nutmeg.
10Bring a pot of 6 quarts of salted water to a boil. Cook the ravioli until al dente. Freshly made pasta cooks quicker than the one from the store. Drain well using a colander and transfer the ravioli to the pan with the tomato sauce. Stir gently to mix well and cook for another minute. Transfer the ravioli to a pasta to individual plates and serve immediately.