In a 2-quart saucepan, whisk together tangerine juice, sugar and vanilla. Whisk n egg and egg yolk.Cook over medium-low heat for about 1 minute. Scrape down sides often. Remove from heat and stir in butter. Return to stove and cook over low heat for about 2 minutesstirring often. Cook until mixture thickens and bubbles begin to form. Pour curd into a bowl a gently press plastic wrap over the surface to prevent water from forming. Chill at least a hour efore using.