To make the peppers, preheat the oven to 450℉ and line a sheet pan with parchment paper and set aside. Slice each bell pepper in half lengthwise, removing the stem and seeds, then place them cut-side down onto the sheet pan.
Roast the peppers for 30 to 40 minutes until the skin is blistered and charred. Remove the pan from the oven and place the pepper halves into a heat-safe container, then cover the bowl tightly with plastic wrap.
Allow the peppers to steam for at least 5 to 10 minutes before removing the plastic wrap and peeling the blistered skin from the peppers. Set aside.
Once the peppers have cooled slightly, place them into the bowl of a food processor with the remaining ingredients.*
Blend everything into a smooth paste, then taste and adjust for seasoning as needed.
Spoon the dip into a serving dish, then garnish with olive oil and serve with pita. If not eating immediately, cover and refrigerate the muhammara, then bring to room temperature when ready to serve.
If kept refrigerated in an airtight container, homemade muhammara will keep for up to a week—drizzling a thin layer of olive oil over the top of the dip will help to preserve it.