Cover the chilies with boiling water and soak for 10 minutes. Drain and roughly chop. Put them in a food processor and add the mint, coriander, cumin, garlic, 1 tablespoon of the olive oil, and ½ teaspoon salt. Process for 20 seconds, scrape down the side of the bowl, then process for another 30 seconds. With the motor running, gradually add the remaining oil, scraping down the side of the bowl when necessary.

Spoon the paste into a very clean, warm jar; cover with a thin layer of olive oil and seal. Harissa will keep in the refrigerator for up to 1 month.