01 - In a medium heatproof bowl, whisk together the eggs, egg yolks, sugar, pink lemon juice, and zest until completely smooth and well combined.
02 - Place the bowl over a saucepan of simmering water, ensuring the bottom of the bowl does not touch the water surface.
03 - Cook while whisking constantly for 8-10 minutes until the mixture thickens considerably and coats the back of a spoon, reaching approximately 170°F.
04 - Remove from heat and whisk in the butter one piece at a time, ensuring each addition is fully melted and incorporated before adding the next.
05 - If desired, stir in raspberry juice or food coloring to enhance the natural pink hue.
06 - Pour the curd through a fine-mesh sieve into a clean bowl to remove the lemon zest and any bits of cooked egg.
07 - Allow the curd to cool completely, then transfer to sterilized jars. Refrigerate for at least 2 hours to set properly. Store chilled for up to 2 weeks.