Slice red onion. Set aside.

Heat olive oil in a large saute pan on medium heat. When oil is hot, add the sausages to the pan. Brown on all sides.

Add the onion to the pan.

Cook onion and sausage until the onions start to caramelize and turn brown.

Add the red wine.

Cover and cook the sausage about 7 minutes. Add the parsley and garlic if using. Remove cover and flip the sausages. They should be picking up the color of the wine. Cook an additional 7 minutes, or until sausage are cooked through. Be careful not to dry out the sauce. Drop the heat if the sauce is evaporating too quickly. Taste the sauce and add salt and pepper if needed.

Transfer sausage to a serving dish and pour sauce on top.