In a medium saucepan, whisk together sugar, cornstarch, and salt. Add mango nectar, and whisk until smooth. Whisk in egg yolks. Cook over medium heat, stirring constantly, until mixture thickens, 7 to 9 minutes. Remove from heat.
Transfer mixture to a heatproof bowl. Cover with a piece of plastic wrap, pressing wrap directly onto surface of curd. Refrigerate until cold, 4 to 6 hours, before using. Store in an airtight container in the refrigerator for up to a week.
Recipe by TeaTime Magazine at https://teatimemagazine.com/linzer-cookies-with-mango-curd/