Roast the eggplant over a medium gas flame or a charcoal grill, turning it frequently with tongs, until the inside is soft and the skin is completely charred on all sides. Let cool, then peel and mash. Put the eggplant in a bowl.
Place a medium nonstick sauté pan over medium heat and add the oil. When small bubbles appear at the bottom of the pan, add the onion