PREPARATION:

1. Combine milk, 3/4 cup sugar and vanilla bean in medium saucepan. Cook and stir over medium-high heat just until milk begins to boil; remove from heat.
2. Cut vanilla bean in half lengthwise. Scrape seeds into saucepan; add bean halves to saucepan.
3. Combine remaining 1/4 cup sugar, whole eggs and egg yolk in large bowl. Beat mixture until frothy and light lemon color. Continue whisking mixture while very slowly pouring in 1 cup hot milk mixture.
4. Slowly pour egg mixture into saucepan with vanilla bean. Cook over medium heat and whisk slowly until first bubble forms. Do not boil.
5. Pour custard mixture through fine-meshed sieve into medium bowl set in ice water; stir custard mixture until cool. Cover and refrigerate about 1 hour or until cold.
6. Combine avocados and lime juice in medium bowl. Mash with wooden spoon or potato masher. Press avocado mixture through fine-meshed strainer with rubber spatula; stir into custard mixture.
7. Freeze in ice cream maker according to manufacturer's directions.