Roll limes or heat in microwave for 10 seconds to get juices flowing. Halve the limes. Rub the avocado halves gently with 1/2 lime to retard the browning. Juice limes into small bowl and mix with sugar, chili powder and salt using a fork or small whisk.
Add extra-virgin olive oil in a slow stream while mixing dressing.
Pour dressing into the cavities of avocados, distributing it equally and serve.
Garnish with chives or cilantro as an optional garnish.
