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Low Carb Rhubarb Custard – Crustless

Low Carb Rhubarb Custard – Crustless

Rhubarb season is brief and there are so many delicious sweet and savory rhubarb dishes to make. This tangy-sweet custard can be enjoyed as a simple custard or as a rhubarb crisp. It is a rich vanilla custard over a layer of tart rhubarb and sprinkled with a nutty streusel topping. It is also easily modified to low carb without a loss in flavor.

Rhubarb custard with low carb nut crisp topping
Rhubarb custard with low carb nut crisp topping
Rhubarb custard with no crust
Rhubarb custard with no crust

How to Purchase, Prepare and Store Rhubarb

For a little background, rhubarb is a vegetable that is used like a fruit in cooking, Rhubarb has pink to red celery-like stalks and large green leaves. The only part of the plant that is edible is the stalk; the leaves are toxic and must be removed and discarded.

The tart-flavored stalks are always served sweetened and cooked. Field-grown rhubarb is available April through July, while hothouse varieties are sold January through June.

Tips for buying and storing rhubarb

  • Select bunches of rhubarb with crisp, straight well-colored stalks. Any attached leaves should look fresh, although they should never be eaten, as they are toxic. Most stores and markets have cut off the leaves.
  • Avoid rhubarb with stalks that are turning green or have blemishes or cuts.
  • Refrigerate unwashed rhubarb in a plastic bag for 3 to 5 days.
  • Freeze fresh, cut-up rhubarb in freezer-weight plastic bags for up to 9 months.

Preparing Rhubarb

  • Trim off and discard all leaves and the ends of the stalks.
  • Remove any brown spots or coarse strings with a vegetable peeler. Wash under cold running water.
  • Cut the stalks crosswise into 1- to 2-inch pieces. Because it breaks down easily during cooking, rhubarb is usually not cut into small pieces.

How to Modify Rhubarb Desserts to Low Carb Desserts

Rhubarb custard and rhubarb custard crisp can easily be modified to be low carb recipes. In general it is a matter of switching white enriched flour to almond flour and switching pure cane sugar to a sugar substitute.

Custards include eggs, cream and sugar. Eggs and cream are staples on a low carb or keto diet so it is mostly a matter of switching out the sugar to a sugar substitute.

My favorite sugar substitute is A monkfruit blend. The monkfruit blends usually include erythritol. The flavor of the custard using this blend is very good. Some people will notice a “cooling” taste from the erythritol part of the blend. Some people also experience digestive issues with erythritol.

Even though erythritol sounds like an artificial compound, it occurs naturally in a variety of foods (e.g., grapes, mushrooms, pears and watermelon) and some fermented foods and beverages like beer, cheese, sake, soy sauce and wine. Erythritol is produced using fermentation.

Crisp toppings are also easy to modify to low carb. Instead of oats, use nuts for a nice crunch. Instead of white refined flour, use almond flour.

Cornstarch is often used to thicken fruit pies. While cornstarch is not low carb, you don’t usually use enough of it to make much of a difference.

Do Custards Require a Hot-water Bath?

While some custards do better cooked in a waterbath, this rhubarb custard dish is easy and successfully sets without a hot-water bath. It helps to use shallow gratin dishes or ramekins (1 1/2 to 2 inches deep).

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Alyssa Olson

Wednesday 10th of June 2020

Can I make the custard in one large dish versus small ramekins? Will this alter the baking time? Thanks!

dorothy stainbrook

Wednesday 10th of June 2020

Yes, you can certainly make it in one large dish. It shouldn’t effect baking time, but I would check on it 5 minutes before the end of baking time. It should have a slight jiggle in the middle of the pie but not the outer edges. All ovens are different, so it’s a good practice to check on things around 5 minutes before the end anyway. Let me know how it turns out. :)


Sunday 31st of May 2020

Our rhubarb plants almost never have any redness in the stalks. This may be because they are in a lot of shade and fairly pitiful specimens. I haven’t ran into problems eating them but we aren’t eating a lot. The toxin in rhubarb is oxalic acid and is probably concentrated mainly in the leaves regardless of stalk color. But oxalic acid is also responsible for the tangy flavor of French sorrel, spinach and kale. You'd probably have eat 10 lbs. of spinach to run into problems, but I suspect there is a lot more in rhubarb and sorrel. Oxalates do damage by producing kidney stones. This isn’t a serious risk for most people in the amounts eaten, although it won’t hurt to drink a glass of water with them. But some people have a predisposition to form kidney stones, and particularly oxalate stones, and need to avoid oxalic acid containing foods altogether.

dorothy stainbrook

Sunday 31st of May 2020

It was always my understanding that it was just the leaves of rhubarb that were toxic. Maybe I’ll do a deeper dive into this based on your comments however. Re the redness of the stalks: it’s variety specific. There are several different varieties of rhubarb ranging from red to speckled to green. Here’s a little paragraph From the link below that talks about varieties:

“Gardeners and pie makers often assume that deep red rhubarb is the sweetest. However, the color of rhubarb actually has very little to do with its flavor. If you’re a fan of bright red rhubarb, guess what? Rhubarb actually comes in several colors, including pink and speckled rhubarb varieties. You may even discover that green varieties of rhubarb are surprisingly sweet, and tend to be more productive!”

Read more at Gardening Know How: Rhubarb Varieties: Types Of Rhubarb For The Garden

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