Now that rhubarb is in season, here is a novel way you can serve it. Baked in a vegan custard and a puff pastry it is a simple recipe to add to your answers to “what do I do with all this rhubarb?” 
I developed this recipe in response to a recipe challenge set by one of my favourite food bloggers, Sonal of Simply Vegetarian. If you are not familiar with her blog, do pay her a visit. Her reliable, delicious and exotic recipes are a credit to the food blogging community.
The conditions of the challenge were to make a vegetarian semi-homemade, that is homemade with a store bought pastry base of any kind. So I purchased a package of puff pastry.
It is really just the beginning of rhubarb season here, and my rhubarb was not quite ready for picking when I baked this. However, a couple of weeks earlier I had started an experiment to force the first shoots. I covered one small patch with a ceramic chimney (actually our well cover) and placed a stone on top – any tall opaque vessel would do. Two weeks later I uncovered my experimental patch and this is what I found.
The covered patch was much taller and ready to pick while the other rhubarb was close to the ground as seen in the above picture on the right. The leaves were smaller and yellowish, but the rhubarb was bright pink or red with snowy white interior.
This variety of rhubarb is usually green inside with only streaks of red on fairly green stalks – fine for cooking but not the prettiest. This was much prettier. It was also sweeter and a lot less fibrous. Of course, any rhubarb will work, but the redder the variety you get, the better the appearance. I will definitely be doing this again next year and more of it.
I also wanted to make a vegan custard. As the challenge is for a vegetarian dish, though not necessarily vegan, I wanted to make it appealing to as many readers as possible. Also, I was running low on eggs. This was definitely another experiment for me, and again one that worked. For the custard-like consistency, I simmered some flax seeds and strained them. A little sugar, cardamom for flavouring and almond milk for bulk, it really couldn’t be easier or more fool-proof.
Rhubarb Tart
Ingredients
500 grams puff pastry
a few stalks of rhubarb
flax seed liquid+
2 cups almond milk
3 Tbsp thickening flour (I used tapioca flour)
1/2 cup sugar
1 tsp freshly ground green cardamom
1 Tbsp rhubarb or other fruit bitters (optional)
Method
+ To make the flax liquid, bring 2 Tbsp flax seeds to a boil in 1 cup of water. Turn the heat down and simmer for 30 minutes, uncovered. Strain the liquid through a fine sieve. Use the seeds in the strainer to add to a smoothie! For a lighter colour than I achieved, use golden flax seeds rather than the dark ones.
Roll out the puff pastry to fit a pan 12 inches by 9 inches and prick all over with a fork. Mix the flax seed liquid, milk, flour, sugar and cardamom and heat gently, stirring frequently, until it thickens and the flour is cooked. It will still be more liquid than the final product since the flax seed won’t set until cooled. When semi-cooled, add the bitters if using them.
Pour the mixture into the prepared pan and place rhubarb pieces of about 3 inches in length and slit lengthwise if very thick neatly on top. Bake in a 350 degree oven until the crust is golden and the rhubarb is cooked, about 30 minutes.

The custard will be very liquid when it comes out of the oven, but will set as it cools. Serve as is or with a dusting of confectioner’s sugar or drizzle of syrup. I used honeysuckle syrup.
Many thanks to Sonal for her initiative and for inspiring me to try something new! I enjoyed every bit of it.