In a medium bowl combine mashed avocados, green onions, 1/3 cup cilantro, sour cream, lime juice, salt, and, if desired, hot pepper sauce.
Divide mixture among three 1-quart freezer bags. Squeeze air from bags, seal, and freeze for up to 1 month.
To serve, thaw overnight in the refrigerator. Garnish with cilantro sprigs and serve with tortilla chips.
If desired, snip off a corner of the freezer bag and use the bag to pipe the guacamole directly onto chips.