Start with the sausage filling. Add the sausage meat to a large bowl with the toasted fennel seeds, parsley, sage, thyme, garlic, Dijon and loads of black pepper. Really work everything together for a couple of minutes using your hands or a wooden spoon, until the sausage meat is slightly sticky and properly seasoned throughout rather than having herbs vaguely scattered through it. Fry off a little piece and taste before adding extra salt; depending on your sausage meat, you might not need much.