Dried chiles are not used right out of the box or bag. If you do that, your finished sauce will taste of little more than mildly hot dust. Roasting the chiles until they’re charred and blistered will intensify their flavor. This is the first step to waking them from their slumber, and it’s critical to get it right. Under-roasted chiles won’t be as flavorful, but over-roasted chiles will impart a bitter flavor that is difficult to combat.

Properly roasting chiles can be done in several different ways. First, assemble them on a baking sheet and roast in a 400 F oven for 20-30 minutes. Turn them a couple of times as they roast, being mindful of any hot spots that are getting darker. Another way to roast chile peppers is on an outdoor grill. Preheat your grill to medium heat, then place the chiles directly on the grate. Flip with tongs as they roast, making sure they evenly cook.

Finally, if you have a gas stove with a smooth hot plate, roasting chiles is simple. Heat up the hot plate, and place your chiles directly on top. Again, keep an eye on the chiles for any hot or burnt spots. If you want to add even more complexity to your sauce, roast your garlic in its papery skin and your unpeeled onions at the same time.