Preheat oven to 400 degrees F. Place eggplant, red pepper, olive oil and salt in a large Ziploc bag. Shake to coat vegetables.
Place prepared vegetables on a rimmed baking sheet. Wrap unpeeled garlic cloves in aluminum foil, and place that on the baking sheet as well.
Roast 40-45 minutes, tossing once halfway. Let vegetables cool for 10 minutes before adding to a food processor, fitted with a steel blade. Add tahini and pulse ingredients for approximately 30 seconds.