Once the flesh has been scooped out, halved avocado skins make pretty single-serving cups for guacamole; serve them on saucers, surrounded by tortilla chips. They make a tasty preamble to a chili supper or a Mexican-style stew such as Vegetarian Posole Stew or Chorizo and Potatoes Tinga.
1. Halve and pit avocados. Score each avocado half 7 times lengthwise and 7 times crosswise to dice. Scoop out with soup spoon, and place avocado dice in large bowl. Reserve avocado shells.
2. Cut peel and pith from oranges with knife, then slice each orange into 4 slices. Cut each orange slice into 6 small triangular pieces. Add to bowl with diced avocado. Add radishes, romaine, green onions, lime juice, cilantro, and hot sauce (if using) to bowl. Season with salt and pepper, if desired, and gently toss to coat.
3. Scoop avocado mixture into avocado shells. Serve immediately.