Put 1 c juice in a small saucepan. Sprinkle all the gelatin over it. Let rest five minutes to soften. Heat juice and gelatin mixture, stirring, until all the gelatin melts and the juice looks glossy.

Mix the yogurt and pesto into the second cup of juice. Stir the gelatin mixture into the seasoned juice.

Fill a tall, narrow container with drinking straws. Pour the juice mixture into the straws and chill until firm, at least several hours.

Unmold. Let rest at least a few hours, preferably overnight, uncovered in the refrigerator, to both chill and dry slightly, until firm to the touch (so that it will stay firm at room temperature.)