Slice the onions, garlic, tomatoes and the rest of the herbs if used as fresh.
In an oven safe dish, mix all the ingredients with the sliced pepper and onion.
Put it into the lover rack of a 400°F / 200°C oven for about 90 minutes or until the desired texture reached.
Advanced - Skillet
Heat oil to medium to high then sear the sausages on both side until golden brown, for about 3 minutes each side. Take them out of the pan if short of space.
Saute sliced onion and salt on high heat until it gets a glassy / translucent look, for about 3 - 5 minutes.
Add the sliced pepper and tomato then saute for another 3 - 5 minutes.
Reduce the heat to medium to low. Mix in garlic, oregano, basil and put the sausages back. Place the lid on and cook for 7 - 10 minutes or until the desired texture is achieved.