Roast tomatillos on a flat grill for 10 to 15 minutes or until soft.
Next roast chiles until soft and cover with hot water in a bowl to soften.
Blend chiles, garlic, and salt until smooth then add tomatillos and pulse blender two to three times to maintain a thick consistency.
The original salsa is actually made with pasilla Oaxaqueños that are produced only in the hilly Oaxaca region of southern Mexico. They have a strong smoky character, a scant hint of fruit, and a heat level that is pure and sharp but not overwhelming. This chile is not very common in the United States so I substituted using regular pasilla chiles