1. Whisk base: In a medium heatproof bowl, whisk eggs, sugar, lemon juice, zest, and salt until smooth.
2. Cook gently: Place bowl over a saucepan of simmering water (double boiler method—bowl should not touch water). Cook, stirring constantly with a silicone spatula, for 8–12 minutes, until thickened and coats the back of a spoon.
   → Tip: The curd is ready when it reaches 170°F (77°C) or leaves a clear path when you run a finger across the spatula.
3. Add butter: Remove from heat. Whisk in butter, one cube at a time, until fully melted and glossy.
4. Strain (optional): For ultra-smooth texture, strain through a fine-mesh sieve to remove zest and any cooked egg bits.
5. Cool & store: Press plastic wrap directly onto surface to prevent skin. Chill at least 2 hours before using.

💡 Pro Tips:
– Use freshly squeezed lemon juice—bottled can taste metallic.
– For longer shelf life, pour hot curd into sterilized jars; keeps up to 2 weeks refrigerated or 3 months frozen.
– Double the batch—it disappears fast!

Prep Time & Nutrition (per 2-tbsp serving, makes ~1½ cups):