In a saucepan, simmer water. In a heatproof bowl, add the purée, eggs, egg yolks, lemon zest, lime juice, salt, ½ cup sugar, and 1 tsp. lime zest. Place heatproof bowl over the top of the simmering water - make sure the water does not touch the bowl. Stirring with a rubber spatula and scraping down sides of bowl often, until curd thickens and coats spatula, 15-20 minutes. Let cool until just warm.