Whisk the yolks, honey, juice, and zest together. Position bowl over a simmering pan of water and stir with a silicone spatula until the curd coats the sides of the bowl and the spoon.

It should be about the thickness of regular whole milk yogurt (not greek yogurt) and will take between 6 and 9 minutes to achieve the proper thickness.

Remove the bowl from the pan and stir in the butter. Once the butter is melted, run the curd through a fine mesh sieve to remove the zest and any scrambled bits.

Pour into a jar and refrigerate. It may look a little runny when it's still warm, but it will thicken up as it cools.

This is not a curd that should be canned. It will keep in the fridge for 10-14 days or can be packed into small jars and frozen for up to 6 months.