There is nothing better than a perfectly grilled, juicy Italian sausage to go with a glass of Sangiovese and your favorite pasta. You cut into the sausage feeling that "snap" of your knife, then the juices flow out onto the pasta, mingling with the sauce. Boiling your sausages before grilling ensures that your sausage will be cooked through, allowing all the juices to stay on the inside while the casing gets brown and crispy on the grill.
Prick each sausage with the skewer a few times on each side.
Lay the onion and garlic, if you are using it, on the bottom of the pot and arrange the sausages on top. If you are using any other liquid besides water, use a ratio of 1 part water to 3 parts other liquid, and cover the sausages completely.
Bring the ingredients to a low boil over medium heat, and then reduce heat to low and simmer for four to five minutes or just until the sausages are slightly firm. Using tongs, remove the sausages from the cooking liquid and drain completely.