Cook the Cotechino sausage, following the instructions on the packaging.
In the meantime, wash and dry the pears, and remove the core, slice each pear into 6 along the length of the fruit.
One by one place the slices in a bowl, then pour the lemon juice over them.
Add the sugar and mix well so that the pears are completely coated.
Prepare a two-handled casserole dish, large enough so that the prepared fruit can be laid out in one layer, and add the vanilla seeds.
Cook on a medium heat, stirring very slowly.
When the juice starts to come out, turn down the heat and remove the slices with a slotted spoon, arrange them in the bowl you used previously. The fruit will continue to release juice, which should be put back in the casserole dish.
Reduce the juice until you get a medium density syrup. Then, put back the slices and mix well so that they are are infused with the syrup.
Pour into a large, shallow terrine and leave it to one side.
Slice the cotechino and put three slices on the upper half of the plate. Lay the slices of pear diagonally underneath and decorate with the syrup.