Frozen Lemon Custard


Many of the world’s best inventions have been discovered accidentally (e.g. safety glass, penicillin and post-it notes). This is what my 7-year-old son told me when we were enjoying the most delicious mistake turned recipe we’ve ever created. In a Kids Cooking Workshop, our lemon meringue pie filling never set. Perhaps it was because we tripled my recipe, overcooked the custard, didn’t use enough thickener or more likely, were distracted with 10 children trying to simultaneously make lemon meringue pies. In any event, we were left with lots of extra unusable pie filling. So I put it into the fridge and decided to deal with it the next day, when I strained it and churned it in my ice cream maker.

The result is a brightly flavored, subtly sweet tart frozen custard with the most luscious texture. It is my new favorite frozen dessert (which is extremely generous because I love a lot of frozen desserts). And it contains no dairy and essentially 5 ingredients (sugar, tapioca, egg yolks, lemons, olive oil). So when life truly gives you lemons… in the form of failed lemon meringue pie filling, make Frozen Lemon Custard and serve it in the food world’s second best accident, an ice cream cone.

A few notes before you begin…

Straining: I tested straining this liquid both prior to refrigerating overnight and after and it works much better if you strain it the second day after refrigerating. The lemon flavor from the zest will be more intense and more time resting with the zest and tapioca creates a thicker smoother consistency.

Lemon zest and juice: You will use about 3 average sized lemons but since size and juice yield varies so much from lemon to lemon, use the measurement above for the juice, and as much zest as your lemons yield. Always zest lemons first before you cut them to press the juice.

Makes: 2-3 pints

What You Need:

  • 2 ¼ cups hot water

  • 1 ½ cups sugar

  • ⅛ teaspoon sea salt

  • 6 tablespoons tapioca starch, sifted

  • 6 egg yolks

  • 2-3 tablespoons finely grated lemon zest

  • ¾ cup freshly squeezed lemon juice

  • 1 tablespoon olive oil

What You Do:

  1. In a medium pot over medium high heat, stir the sugar and salt into the hot water, until dissolved. Whisk in the sifted tapioca starch until thoroughly combined. Stir until mixture thickens enough to coat the back of a spoon, about 3 minutes. It will be a thick syrup. Don’t worry about lumps of tapioca. You will strain those out later.

  2. Temper the eggs: Turn off the heat. In a small mixing bowl, whisk the egg yolks, and then slowly whisk about ¼ cup of the sugar mixture into the egg yolks. Slowly whisk the egg mixture into the pot, and turn on the heat to medium high. Whisk constantly and bring to a boil. Cook on medium high heat, whisking continuously for 3 minutes. 

  3. Add lemon zest and juice and whisk briskly for about 30 seconds.

  4. Add the olive oil. Stir. Turn off the heat. Let it cool slightly.

  5. Transfer the cooked custard to an ice bath to cool completely.

  6. Transfer to a container with a tightly fitting lid, cover and refrigerate overnight. Meanwhile, freeze the ice cream bowl of your ice cream maker.

  7. The next day, strain the custard through a fine mesh strainer. Using the back of a ladle or rubber spatula, gently press the mixture through the strainer to get as much as you can. Discard any lumps or zest left behind.

  8. Freeze custard in your ice cream maker according to instructions. Serve immediately as soft serve or transfer to pint containers and freeze to harden.