Meyer Lemon Curd

Prepare and ice-water bath. Set a medium bowl in ice-water bath and set aside. Place sugar and lemon zest in a mortar and grind with a pestle to combine and release the oils. Transfer sugar mixture to a medium heatproof bowl along with eggs and egg yolks; whisk to combine. Place over a saucepan of simmering water and whisk until sugar has dissolved. Add lemon juice and continue whisking until mixture is thick and reaches 160 degrees on an instant-read thermometer, scraping down sides of bowl as necessary. Add butter and whisk until well combined. Strain lemon mixture through a fine mesh sieve set over prepared bowl. Cover lemon curd with plastic wrap, pressing plastic wrap directly onto surface. Transfer to refrigerator until completely chilled.