Q&A for How to Cook Italian Sausage

No, not really. The sausage will be dry and the peppers will be mushy. You need to either sauté or bake, both of which are very easy.

Usually at a butcher shop, and perhaps at a local deli. You can buy them online as well.

Don't boil them. Although it is time consuming, slowly simmer or poach them by cooking them in water (optionally adding beer and seasoning with garlic). Cooking them in water will make a milder-tasting sausage, as it will remove some of the excess saltiness from the meat. Let them cook slow and easy. Do not pierce the casings, as it will let the juices out. It doesn't hurt to check then with a thermometer to make sure they are done. Serve in your favorite sauce or with peppers and onions.

Sure, if that is the flavor combination you enjoy the most, then by all means add tomato sauce to your cooked Italian sausage.