Once the peppers are cool enough to handle, peel the translucent “skin” off, you can use the back of a knife to help you scrape it off, removing as much as you can. Remove the stems and seeds as well. Break up the peppers roughly and add to a food processor. Cut the top off the garlic bulb and squeeze out the soft garlic into the food processor, making sure to keep the papery skins out. Peel the onion and add it to the food processor as well. Pulse the vegetables until uniformly chopped – you can leave them as chunky or fine as you wish. Set aside.