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 bowl bottom does not touch the water surface to create gentle, indirect heat.
03 - Cook the mixture, whisking constantly to prevent scrambling, for 8-10 minutes until thickened and coating the back of a spoon (approximately 170°F).
04 - Remove from heat immediately. Whisk in the butter pieces one at a time, allowing each piece to fully melt before adding the next, until emulsified and silky.
05 - Stir in raspberry juice or natural food coloring if a deeper pink hue is desired, mixing gently to incorporate evenly.
06 - Pour the curd through a fine-mesh sieve into a clean bowl to remove zest and any cooked egg bits for an ultra-smooth texture.
07 - Let cool to room temperature, then transfer to sterilized jars. Refrigerate for at least 2 hours to set completely. Keeps refrigerated for up to 2 weeks.