To make the filling, put the mortadella, ricotta, and egg in a food processor and puree until smooth and fluffy, scraping down the sides of the bowl as needed. Season with salt and pepper.
To make the pesto, put the nuts in a food processor and chop until fine. Add the oil and vinegar and process to a coarse puree. Taste and season with salt and pepper. Refrigerate the pesto in an airtight container for up to 1 week, or freeze it for up to 2 months.
To make the dough, put the flour in the bowl of an electric mixer fitted with a dough hook. Add the eggs and turn the machine on to low to allow the flour to slowly absorb the eggs. Scrape down the sides if needed. When the dough begins to come together in a ball, turn the speed up another notch and allow the dough hook to knead the dough for a few minutes. Remove the dough from the mixer and knead by hand for a few more minutes until it is nice and smooth. Wrap the dough in plastic wrap and set aside at room temperature for 30 minutes to rest.
To assemble, roll out the pasta dough in four batches using a pasta roller (I prefer the Kitchenaid pasta roller attachment). Roll the pasta as thin as possible without tearing it (#5 on the Kitchenaid attachment is good), and then lay one sheet at a time on a lightly floured surface with one long side parallel to the edge of the counter. Trim the sides and ends so they are straight, then cut the pasta into 3-inch squares. If necessary, spritz lightly with water to keep it from drying out.
Put teaspoon-size spoonfuls of filling on each square, then bring the opposite corners together over the filling to make a triangle. Press gently on the edges to seal. Trim the edges, if desired, to make for a more aesthetic presentation. Makes about 45.
Bring a large pot of salted water to a boil. Drop in the tortelli, quickly return to a boil, and cook until tender yet firm, 3 to 4 minutes. Drain the pasta reserving the pasta water.
Just before the pasta is done, ladle 3 cups of the pasta water (I suggest going a little shy on the pasta water here) into a large saute pan. Add the pesto and bring to a boil over medium-high heat. Boil until the sauce is creamy, about 2 minutes.
Slide the drained tortelli into the warm sauce. Toss gently until the sauce is creamy, adding more pasta water as needed.
Divide among warm pasta bowls and garnish with the Parmesan.
Notes
Prep Ahead: The tortelli can be assembled, tossed with flour, and frozen in an airtight container for up to 3 days before cooking. Take the tortelli right from the freezer to the pasta water.Adapted from Rustic Italian Food