Preheat oven to 400 degrees. Place eggplants, cut sides up, on a rimmed baking sheet, and brush with 1/2 teaspoon oil. Scatter garlic over tops, and sprinkle with salt. Roast until golden and tender, about 20 minutes. Let cool slightly.
Remove eggplant seeds; spoon flesh and garlic into a food processor. Puree; transfer to a medium bowl.
Add olives to processor, and pulse until coarsely chopped. Add to bowl with eggplant mixture. Stir in chopped oregano, lemon zest, red-pepper flakes, and remaining teaspoon oil. Garnish with oregano leaves and lemon-zest strips. Serve with bell peppers.