Whisk together your 3 eggs, 1 cup sugar, lemon zest, and salt in a medium bowl until combined. The mixture should look pale and slightly fluffy. Don't skip the whisking—it aerates the eggs and helps prevent lumps in your finished curd.

In a separate small bowl, mix together the 1/4 cup water, cornstarch, cream of tartar, and baking soda until smooth. This stabilizer mix is what gives you that perfect creamy texture. Stir it into your egg mixture until fully incorporated.

Pour the 1/2 cup lemon juice into your egg mixture and whisk everything together until smooth. The juice will look like it's separating a bit—that's totally normal and actually what you want.

Set a heatproof bowl over a pot of simmering water (not touching the water), creating a double boiler setup. Pour your lemon mixture into the bowl and add the 1/2 cup butter cut into small pieces.

Stir constantly for about 10-12 minutes until the mixture thickens and reaches 160°F on a candy thermometer. I always stir in the cardamom at this point—that's when it blends best. Your curd should coat the back of a spoon.

Remove from heat and stir in the orange blossom water. Let it cool for 5 minutes, then strain through a fine-mesh sieve to catch any cooked egg bits. This step made my homemade lemon curd summer so much silkier.

Pour into clean jars and let cool completely before covering. It'll thicken more as it cools—don't panic if it looks thin at first. Refrigerate until you're ready to serve.