Wash the red peppers and place them in a dish under the broiler until the flesh softens and the outer skin burns and turns black. It is important to turn the peppers midway through, so that they cook evenly on all sides.
While the peppers are broiling, pour the olive oil in a small pot or pan, add the peeled garlic cloves and place on low to medium heat. Roast the garlic for a few minutes until they soften and turn slightly golden. As soon as the garlic is cooked, spoon them out of the oil to prevent them from burning.
When the peppers are done, place them in a bowl, cover them with foil and let them rest for about 5 minutes. This will help them steam up and make them easier to peel.
Peel the black outer skin from the peppers, remove the seeds and place them in a blender.
Add all the ingredients (including the olive oil used for roasting the garlic) apart from the vinegar and salt and pepper to the blender and blend until the desired consistency is achieved.
One the ingredients are blended, taste the sauce to understand the seasoning required. If you want to make the sauce tangy, add the vinegar. It is very likely that you'll need to add the whole teaspoon of vinegar, but feel free to add more or less depending on your taste. Also season with salt and pepper.
Scoop it out of the blender and place in a bowl. You can serve the sauce immediately or you can leave it in the fridge for a few days. I find that the sauce tastes better if left to rest in the fridge for at least a few hours!