Fair warning: this salsa can be addictive! I first tasted it in Ixtapa, Mexico, and after that, I had to figure out how to make it myself at home. Fortunately it is actually a very simple salsa, and tastes so great with a bowl of tortilla chips and a nice cold beer on a sunny day. The creaminess of the avocados combined with the pop of spice from jalapeños and serranos make this salsa irresistible. Use this salsa to top tacos, gorditas, or sopes.
Preheat the oven to broil. Roast the tomatillos, serrano peppers, jalapeños, and garlic on a foil-lined baking sheet until blackened all over, about 5 minutes. Flip them over and roast the other side for an additional 4 to 5 minutes. Watch carefully to prevent the tomatillos from burning.
Place roasted peppers in a plastic bag, close the bag, and allow the peppers to steam until the skins loosen, about 10 minutes.
While the peppers are cooling off, peel off skin from garlic and discard. After the peppers have steamed, peel skin off and discard.
Place in a blender the cooled tomatillos, roasted and peeled peppers, roasted garlic, avocados, cilantro, water, and salt. Blend until creamy.