Wash and chop the tomatillos into quarters, halve the avocado and scoop out the inside, and slice the lime.
Combine the avocado halves, tomatillos, sour cream (optional), ranch dressing mix, lime juice, chopped cilantro, garlic powder, and salt & pepper together into a blender or a bowl. If you want it spicy, add in a jalapeño or a pinch or two of red pepper flakes.