Chef John's Harissa Sauce
If you have a gas stove, you may use an open flame to roast the red pepper. Turn heat to medium high and roast pepper over the flame, turning occasionally until the skin has blackened and blistered, 8 to 10 minutes. Place peppers in a bowl, cover with plastic wrap, and let steam. When cool, strip and discard skins.
Substitute any red chiles for Fresno chiles.