Heat the oven to 200C/390F/gas mark 6. Put the peppers on a tray and roast for 30-35 minutes, turning occasionally, until they are cooked and the skin is blackened. Put the peppers in a bowl, cover with cling-film and, once cool enough to handle, peel and discard the skin and seeds.
Pat the peppers dry, and place in a mortar. Add the breadcrumbs, lemon juice, molasses, cumin, chilli and garlic. Work this with a pestle until well combined, but not so much that the peppers no longer have a noticeable texture.
Stir through the walnuts, a quarter-teaspoon of salt and the olive oil. Add more pomegranate molasses and salt to taste – you want the flavours to be pretty intense. Spoon the dip into a shallow bowl, using the back of a spoon to give it a wavy texture, and drizzle with a little olive oil. Serve at room temperature.