Preheat oven to broil or 550 degrees and line a baking sheet with foil. Place the bell peppers on the baking sheet. Wrap the garlic cloves in a small piece of foil and place on the baking sheet with the peppers. This will ensure that the garlic doesn't burn to quickly.

Broil the peppers and garlic until the entire pepper is softened and you can see black char, about 10 to 12 minutes. Once done, remove the peppers from the oven and cover with another piece of foil and allow to cool enough to handle. This also helps make the outer charred skin easier to remove.

Once cool enough to touch, remove the skin, seeds and stems from the peppers and place the flesh in a food processor along with the roasted garlic cloves.

Add the tomato paste, cumin, paprika, oil and lemon juice and zest to the food processor and pulse until there is a smooth yet coarse consistency. Taste for seasoning and add salt as needed.

Pour the harissa into an airtight container and keep in the fridge for up to 4 days.