Preheat oven to 450º F. Halve eggplants lengthways and make a few shallow cuts with a knife on its flesh. Brush with olive oil and season with salt and pepper.
Wrap the garlic loosely in foil and place both on a baking tray, allowing to roast until browned and very soft (probably around 25 min, but check as you go, and leave in a little longer if you need).
Scoop out the eggplant flesh and squeeze out the roast garlic puree. Discard the skins of both. In a food processor, combine all ingredients until smooth.
Season with sea salt and black pepper to taste. Serve with a drizzle of olive oil and a sprinkle of sumac or harissa seasoning.