Preheat the oven to 350 degrees. Cut the eggplant length-wise and place the cut sides down on an oiled cookie sheet. Roast about an hour or until it is soft and starting to collapse.Allow it to cool enough to handle, and scoop the flesh out into a colander to drain it. Place 3/4 of the eggplant into a food processor with the garlic, lemon juice, tahini and salt and blend.Mash the remaining eggplant, leaving some chunkiness to it. Combine the blended mixture with the chunkier eggplant, drizzle with olive oil, stir, and taste for salt.