Preheat oven to 450° F. Cut ends off eggplant and cut lengthwise in half, Cut peppers in half and remove seeds. Generously oil and salt both eggplant peppers and place flesh side down onto a foil line rimmed pan. Roast in oven for 40 minutes, until eggplant is soft and the red peppers skins are charred. Remove from oven and allow to cool for 20 minutes.
While the vegetables are cooling, In a large bowl mix the tahini, lemon juice, 2 tablespoons of the olive oil, yogurt, minced garlic, cumin, smoked paprika, salt, and pepper until smooth and well combined.
Remove the skins from the peppers, chop the flesh to a fine mince and to the spiced sauce bowl. Separate the flesh from the eggplant skin using a spoon, remove any large clumps of seeds. Place the pulp into a mesh colander (strainer) over a small bowl. Using gentle pressure press down on the eggplant to allow any excess liquid to drain. Place eggplant into the spices sauce bowl and using a fork mash until completely incorporated, leaving some chunky pieces of eggplant. Garnish with parsley and red pepper flakes, optional: top with a dollop of harissa paste. Serve at room temperature.