Hard-boil the eggs: In a pot large enough to fit all the eggs in a single layer, bring water to a boil (enough water to fully submerge the eggs). Carefully lower each egg into the simmering water. Cover with the lid, let the eggs simmer for 1 minute, and then turn off the heat. Let the eggs sit in the hot water, covered, for 14 minutes. Once ready, rinse the eggs over cold water and peel them. Tip: If you can, cook an additional 1 or 2 eggs just in case one breaks while peeling.
Cut each egg in half lengthwise. Remove the egg yolks into a bowl and cover it. Refrigerate the egg whites and the egg yolks for 30 minutes (or overnight, if preferred).
Make the avocado filling: In a bowl, mash the egg yolks, avocado, garlic powder, mayonnaise, freshly squeezed lime juice to taste, and cilantro or chives (optional). Season with salt and pepper to taste. Adjust the consistency if needed: For more moisture, add more mayo. For more acidity, add more lime juice.
Add the filling to a Ziploc bag and snip off the corner. Pipe the filling into the egg whites. Note: If using a piping tip, insert the piping tip into the corner of the bag first and then snip off the corner. Then add the filling and pipe.
Garnish with more chives or cilantro if desired. Serve immediately.