Place on a baking tray lined with tin foil and roast at 200 degrees C for 20 minutes. Remove from oven, turn peppers over and return to the oven for another 20 minutes until the skins are looking charred and the peppers are soft. Leave in the oven for a few more minutes if they need longer.
Remove from the oven and allow to cool for 10 minutes, or until you can handle them.
Slice the peppers vertically and open them out. Remove the stalk and most of the seeds should come with it. Use a spoon or a paper towel to remove the remaining seeds.
Flip the pepper over and peel off the skin.
Use immediately or store in the fridge in an airtight container. If storing for more than a couple of days, cover in olive oil.