- Preheat your oven to 180°C / 356°F 
- Cut the bellpepper in half, remove the stem and the seeds and place them with the cuts down in an ovenproof dish. 
- Rub the bellpeppers with a bit of olive oil and place in the middle of the oven. 
- Leave in there until they turn soft and the skin starts to turn black on top. 
- Take them out, leave them under a damp towel for 5 min and then remove the skin. 
- Slice the bellpepper and salt them lightly. 
- Layer a slice of bread with mozarella, the sliced bellpeppers, sprinkle with onions and finish with a piece of mozarella or two before you put on the top slice of bread. 
- Butter the outside of the sandwich lightly and place in a pan oder medium-low heat. 
- Turn frequently until the bread is brown and crispy and the cheese is melted.