Preheat the oven to 450°F (230°C). Place the 4 red bell peppers on a baking sheet and roast until their skins are blistered and charred, turning occasionally.

Transfer the roasted red bell peppers to a mixing bowl. Cover the bowl and let the peppers steam for 10 to 15 minutes.

Peel the steamed red bell peppers and discard their skins, stems, and seeds. Roughly chop the peeled peppers.

Heat 1 tablespoon of olive oil in a skillet over medium heat. Add the diced onion and halved garlic cloves.

Sauté the onion and garlic for 3 to 5 minutes. Cook until the onion is translucent, then remove the skillet from the heat.

Lightly toast 1 cup of walnuts in a dry skillet over medium-low heat. Remove the walnuts when fragrant and cool them briefly.

Reserve 2 tablespoons of toasted walnuts for garnish. Add the remaining toasted walnuts to the food processor.

Add the roasted red bell peppers, sautéed onion, and sautéed garlic to the food processor. Add 1/2 cup breadcrumbs.

Add the sumac, ground coriander, paprika, salt, ground cumin, and Aleppo chili pepper flakes. Add the tahini paste and pomegranate molasses.

Add the lemon juice, 2 tablespoons of olive oil, tomato paste, and bell pepper paste. Blend until the dip is smooth and thick.

Taste the muhammara and adjust the salt, ground cumin, or Aleppo chili pepper flakes if needed. Blend briefly after each adjustment.

Spread the muhammara onto a serving plate. Drizzle the remaining 2 tablespoons of olive oil over the top.

Crush the reserved toasted walnuts and scatter them over the dip. Garnish with pomegranate seeds and chopped fresh parsley.