Hard-boil the eggs: Add water into a medium pot, enough to fully submerge the eggs in one layer. Over medium-high heat, bring to a simmer. Carefully lower each egg into the simmering water over low heat. Cover and simmer for 1 minute, and then turn off the heat. Let the eggs sit in the hot water, covered, for 14 minutes. Once ready, transfer to a bowl with iced water and let them cool completely. Tip: use a timer, as even 1 extra minute can cause them to overcook.
Peel and cut each egg in half lengthwise. Scoop out the yolks and transfer to a bowl. Meanwhile, you can store the egg whites in the fridge - the colder, the better.
Make the avocado filling: In a bowl, mash the egg yolks, avocado, freshly squeezed lime juice, Greek yogurt, chopped cilantro or chives, garlic powder, salt and pepper to taste. Adjust the consistency if needed: For more moisture, add more yogurt. For more acidity, add more lime juice.
Arrange the egg white halves on a deviled egg serving platter.
Transfer the filling into a Ziploc bag and snip off the corner. Pipe the filling into the egg whites. Note: If using a decorative piping tip, insert the piping tip into the corner of the bag first and snip off the corner. Add the filling and pipe.
Garnish with more chives or cilantro. If desired, sprinkle with cayenne pepper or paprika. Serve immediately. Enjoy!