Preheat oven to 220C/430F. Poke eggplants and bell peppers all over with a fork. Roast in the center of the oven for 45 minutes (eggplant) and 35-40 minutes (bell pepper) until charred and soft. Rotate halfway through.
Once cool enough to handle, remove the skins from the eggplants and bell peppers. To remove the flesh from the eggplant: cut in half and scoop out the flesh with a spoon. (photos above)
Set eggplant in a strainer to drain its liquid for an hour and 30 minutes.
While the eggplant is draining prepare the tomato puree. Cut an x into the bottom of each tomato. Boil for 3-5 minutes then place in cold water for 3-5 minutes. Peel skin and blend with hand mixer or blender.
Thinly dice onions (and peppers if using). Add oil and diced onions to pot.
Roughly chop eggplant and bell peppers to form a loose, thick paste.
Roughly grind peppercorn in mortar and pestle
Add eggplant, bell pepper, tomato puree, bay leaves, peppercorn and salt to pot.
Bring to a boil then reduce to simmer for 90 minutes.
Adjust seasoning to desired taste and enjoy! You can serve this immediately however it drastically develops flavor over time so I recommend a night in the fridge first.