Step 1

Heat a cast-iron skillet to medium heat. Add the chiles and toast until lightly browned, two to three minutes per side. Editor's Tip: Toasting the chiles in a dry skillet brings out their flavor for a deeper, richer salsa. You'll know they're finished toasting when they're lightly browned, aromatic and start to pop.

Step 2

Transfer the chiles to a bowl and cover them with water. Let them sit for 10 minutes. Drain the chiles and discard the liquid. Editor's Tip: Use warm water to help the chiles rehydrate, becoming soft and plump enough to blend.

Step 3

Add the tomatillos, onion and garlic to the pan used to toast the chiles. Toast until they're lightly browned, seven to eight minutes per side. Then, remove them from the pan and place them aside to cool.

Step 4

Place the chiles, tomatillos, onion, garlic, oil and salt in a food processor or high-powered blender. Puree until smooth.