Step 1Heat a large saute pan over medium heat. Add the oil and onions and saute the onions until they are translucent and tender, 8 minutes. Stir in the chopped garlic, being careful not to burn. Quickly add the eggplant, orange juice and herbs. Continue to cook over medium heat until the eggplant breaks down and becomes a paste, about 2 hours. Stir occasionally so that the eggplant does not burn on the bottom of the pan as it cooks. Remove the pan from heat and wait until cool enough to handle, 10 to 15 minutes.
Step 2Place parchment paper on a work surface. Push the eggplant mixture through an inverted tamis with a plastic pastry scraper. Season the mixture with one-half teaspoon salt and a pinch of pepper.
Step 3Place the mixture in a food processor with the raisins and orange zest; puree until smooth and emulsified, about 3 to 5 minutes. Transfer to a bowl and serve.