Put the aubergine on a baking sheet (as whole) and put it in the oven for 35-40 minutes, or until tender.
Cut the onion into wedges and the bell pepper into 4 pieces. Put these in a baking dish and rub them with oil.
Put the dish in the oven for about 25 minutes, or until the veggies are tender.
Take the dish out and transfer the pepper and onion into a bowl. Cover the bowl with a plate for 10 minutes.
When the aubergine is cooked through, remove it from the oven and let it cool for a few minutes, then scoop out its flesh.
Remove the skin of the onion and pepper.
Put the flesh of the roasted vegetables into a bowl and rest until you want to carry on with the recipe. You can chill it for up to 3 days in the fridge.
Put the flesh and all other ingredients into a blender and whiz until you get a smooth paste.
Taste and adjust it to your liking.