Add the lemon juice, honey, zest, and salt to the saucepan.
Whisk to combine and heat just until warmed.
In a separate bowl, lightly beat the egg and egg yolks.
Remove the honey/lemon juice mixture from the heat, and slowly add about 1/4-1/2 of it into the egg mix, all while constantly whisking. This is called tempering, where you're slowly warming the eggs, so as to not scramble them.
Once the egg mix is tempered, place the pan back onto the heat and whisk the tempered egg mix back into the pan with the remaining honey/lemon juice mixture.
Bring the heat up to medium and stir the mixture.
Continue to stir the curd constantly for 5-8 minutes, until it is thickened and bubbly.
Remove the pan from the heat and cool a bit.
Pour the curd into a container and chill it for 2-3 hours until it is cold and thick.