Scrape the seeds from vanilla bean with the back of a knife.
Combine juice, agar flakes and vanilla seeds and bean in a 2 quart sauce pan. Bring to a simmer and cook gently until agar is dissolved, about 8 minutes. Stir the kuzu in the cold juice to blend and add it to the pot. Stir well. Cook 1 minute, then place the pears in an attractive serving bowl and pour on the cooked juice, discard the vanilla bean and allow to cool. Refrigerate to set.
