Q: I recently made my first tarte au citron using this recipe from The Guardian. It came out great, but the lemon curd filling wasn't thick enough to properly hold its shape after cutting. To take this recipe from being utterly delicious to perfect I need your help. How can I thicken it?
Sent by Lena
Editor: Lemon curd won't cut quite as smoothly as, say, a firmly-set custard or Jello, but it shouldn't puddle out onto the plate after you remove a slice. To make it thicker and more sturdy, try either adding another egg yolk or removing one or two egg whites (using just the yolks).
Readers, do you have any other suggestions for making the perfect lemon curd?
Related: Cara Cara Orange Curd
(Image: Emma Christensen)
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I wouldn't change anything about the eggs. Either cook it down longer (I'm betting this might be the problem...), or add in a bit of cornstarch to help it set.
Use a mix of whole eggs and yolks. Suzanne Goin's filling in Sunday Suppers at Lucques slices perfectly if allowed to chill thoroughly (it will be slightly loose when chilled only a few hours; make it in the morning for dessert, and it will slice cleanly). Also, I strongly dislike curd recipes using measurements such as "juice of 5 lemons." Lemons have differing amounts of juice; you may not have used as much as the recipe writer did, and the amount of acid will affect the set.
Lemon curd is done as soon as it thickens; cooking it further won't make it thicker. Cornstarch would give you lemon pie filling.
I would just make Smitten Kitchen's Whole Lemon Tart: http://smittenkitchen.com/blog/2009/02/whole-lemon-tart/
It is very easy, very delicious, and slices perfectly.