Preheat the broiler and place a rack in the upper third of the oven.
Arrange the bell peppers on a foil-lined baking sheet.
Broil the peppers, turning two or three times, until charred all over, about 30-35 minutes.
Place the peppers in a heatproof bowl and cover. Allow to stand for 10 minutes. When the peppers are cool enough to handle, slip of the skin, and remove the stems, core, and seeds. Set aside.
In a large skillet, heat the olive oil over medium heat. When the oil is hot, add the cherry bomb peppers and garlic. Saute the hot peppers and garlic over medium-low heat until soft and golden, about 10 minutes. Do not allow the garlic to burn.
Place the bell peppers, sauteed garlic, hot peppers, lemon juice, cumin, and salt in the bowl of a food processor Pulse until the mixture resembles a slightly chunky paste, adding more olive oil if necesary. Taste and adjust seasonings.
Transfer the harissa into clean and sterilized glass jars, leaving 3/4 inch (2 cm) of headspace. Add a layer of oil to the top of the jar. (Do not add oil if you are planning to freeze the harissa.) Store in the refrigerator until needed.