Preheat oven broiler and line a baking sheet with aluminum foil.

Place bell peppers cut-side down on the baking sheet.

Roast under the broiler until the pepper skin blackens and blisters (5-8 minutes).

Toast bread slices and let them cool.

Crush toasted bread slices into crumbs using a rolling pin in a sealed bag.

Transfer roasted peppers to a bowl and seal with plastic wrap for 15 minutes to loosen the skin.

Remove and discard pepper 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.

Run the food processor at the lowest setting, slowly streaming in olive oil until fully integrated.

Transfer the mixture to a serving dish.

Sprinkle sumac over the mixture to serve.