To make the pasta dough, mix the cassava flour, eggs, xanthan gum, olive oil, and salt together in a large bowl until the dough forms.
Knead the dough on a lightly floured surface for about 8-10 minutes, or until it is smooth and elastic. Wrap the dough in plastic wrap and let it rest for 30 minutes.
To make the filling, mix together the ground beef or pork, Parmesan cheese, ricotta cheese, parsley, pepper, and salt in a large bowl until well combined.
Roll out the pasta dough on a lightly floured surface to about 1/8 inch thickness.
Cut the pasta dough into 2-inch circles using a round cookie cutter.
Place a small spoonful of the filling in the center of each pasta circle.
Fold the edges of the pasta circles up to form a half-moon shape, then pinch the two opposite corners together to form a ring. Repeat with the remaining pasta circles and filling.
Bring a large pot of salted water to a boil. Add the tortellini to the boiling water and cook for about 2-3 minutes, or until they float to the surface.
Serve the tortellini with your favorite pasta sauce, grated Parmesan cheese, and freshly chopped parsley, if desired. Enjoy!