Pre-heat the oven to 450 F. Wash the vegetables while it heats. Cut the top off the garlic so that a bit of each clove is exposed, then smear the top of the garlic head with olive oil. You should only need 1/4 tsp or so. Wrap the garlic head in aluminum foil.
Cover a baking sheet with parchment paper, and place the vegetables on it. Place the baking tray and the garlic in the oven to roast for 40 minutes or until the vegetables are well charred.
When the vegetables are well charred, take them out of the oven, and let them cool a bit.
De-seed the roasted peppers and core the roasted tomatoes. Squeeze the roasted garlic from its peel. Add the vegetables and all the other sauce ingredients to the blender. Blend until smooth. Adjust salt as needed. Store in the fridge up to a week.