15 minutes, plus 2 hours, 45 minutes freezing time
The glace is best made a day ahead and refrigerated in a rectangular glass dish. Put the glace into the freezer about 3 hours before the party and stir three to four times during freezing, as for a granita.
2 large ripe Hass avocados
1/3 cup diced onion
Juice from 2 limes
1 1/2 cups Greek yogurt
1 jalapeño, seeded and diced
1 1/2 teaspoons kosher salt
1/2 cup tomatoes, cut into small dice
3 teaspoons best-quality olive oil
Cilantro leaves for garnish
1. Scoop out the avocado flesh
and place it in a food processor. Add the onion, lime juice, yogurt, jalapeño and salt and process until smooth.
2. Put the mixture
into a shallow rectangular glass dish, cover and freeze, stirring the mixture with a fork every 30 minutes to maintain a creamy consistency, until the glace is scoopable, about 2 hours, 45 minutes.
3. Serve two small scoops
in each of six highball glasses. Add a sprinkle of diced tomato, a drizzle of olive oil (about one-half teaspoon in each glass) and three to four cilantro leaves.