"This is a traditional hot pepper dip/spread from Aleppo, Syria. It is quite popular in eastern Mediterranean dishes, especially Turkey. This is very traditional and authentic, and I am sure you will enjoy! Serve with traditional Turkish pide (or your favorite flat bread) or spread on crackers."
Set oven rack about 6 inches from the heat source and preheat the oven's broiler. Line a baking sheet with aluminum foil.
Place the bell peppers with cut sides down onto the prepared baking sheet; roast under the preheated broiler until the skin of the peppers has blackened and blistered, 5 to 8 minutes.
Toast the bread slices in a toaster and let cool; place into a resealable plastic bag, squeeze out air, seal bag, and crush with a rolling pin to make crumbs.
Transfer peppers to a bowl and tightly seal with plastic wrap. Set aside until the skins of the peppers are loose, about 15 minutes; remove and discard skins. Mash the peeled peppers with a fork.
Combine mashed peppers, bread crumbs, walnuts, lemon juice, Aleppo pepper, pomegranate molasses, garlic, cumin, and salt in a food processor; pulse the mixture a few times to blend before running at lowest setting. Slowly stream olive oil into the pepper mixture as it blends until integrated completely; transfer mixture to a serving dish. Sprinkle sumac over the mixture to serve.