Prepare the Eggs - Cut the eggs in half lengthwise and transfer the yolks to a food processor.
Make the Filling - Add the avocado, sour cream, lemon zest, lemon juice, apple cider vinegar, garlic powder, parsley, chives, salt, and pepper. Process on high speed until smooth, about 1 minute. Alternatively, in a large bowl, mash the ingredients together, then mix until smooth.
Fill the Eggs - Transfer the mixture to a piping bag fitted with a large star tip. Pipe into each egg white half. Alternatively, spoon the mixture into each egg white.
Serve - Top with sliced radish and chives. Transfer immediately to a platter or refrigerate until ready to serve.
Notes
Make Hardboiled Eggs: Fill a pot with water to cover the eggs by 1 inch once added. Bring to a low boil at 200°F (93°C), do not go above. Add eggs and boil for 30 seconds. Cover and reduce heat to low. Cook for 12 minutes. Alternatively, steam for 13 minutes. Immediately transfer to an ice bath for 15 minutes.
Make Ahead: Hard-boiled eggs can be made a week in advance.
Storing: Refrigerate in an airtight container for up to 1 day.