Bring a pot of water to a boil and stir in tomatillos and jalapenos. Boil until tomatillos turn bright green and soft, about 10 minutes.

Place cilantro, avocados, cooked tomatillos, and cooked jalapenos into a blender, working in batches if necessary. Blend until smooth, 1 to 2 minutes. Add about 1 tablespoon of tomatillo cooking water, or as needed, if salsa is too thick.

Stop the blender, and season the salsa with garlic powder and salt to taste. Blend again briefly to mix in the seasonings. Transfer to a bowl for serving.