Place a rack in upper part of the oven and turn the broiler on high. Broil peppers on baking sheet, turning on occasion, until flesh is soft and skins are charred, about 12 to 15 minutes. Transfer bell peppers to a medium bowl and cover tightly with plastic wrap for about 10 minutes so that they can steam.
Remove skins from bell peppers (doesn't have to be perfect), remove and discard ribs and seeds. Combine red bell peppers, chickpeas, lemon juice, tahini, garlic, harissa, cayenne and salt in a food processor. Process until smooth, about 1 minute.
With the motor running, add the olive oil and continue to process until hummus is creamy, about another minute. Taste and season with salt. Transfer hummus to a bowl, drizzle with more olive oil, cilantro sauce and cumin roasted chickpeas.