I had the most amazing dried rhubarb at One Tree Grill some time ago and cannot get it out of my head. Is there any way you can do this method as a home baker?
It's always tricky to answer a question about a dish at any restaurant other than my own, as I really have no idea what they have done themselves. I don’t know what it looked like (was it thinly sliced or sliced thickly crossways, or something else) was it crisp or firm, pink or green? I’d suggest you ask them next time you’re in as I do think most chefs are keen to share their knowledge with inquisitive diners. Having written that, what I would possibly do is this:
Cut the rhubarb into 6-8cm lengths then thinly slice it lengthways, about 3mm thick. Make a sugar syrup by boiling 200g caster sugar with 200g water for 1 minute. Leave to cool then dip each slice of rhubarb into the syrup briefly to coat on both sides and sit on a cake rack to drain. Line a baking tray with non-stick paper, or a more commercial sil-pat (a silicon mat from baking stores or online) and lay the slices on, 1cm apart. Dry in an oven set to 90C, fan on half, until dry and crisp, anywhere between 1 ½ and 2 ½ hours. You may find that the baking parchment blows around and if this is the case, sit a cake rack on top of it, using the ‘legs’ to pin it down. If the rhubarb darkens, decrease the temperature. If it doesn’t dry after 2 hours, increase the temperature slightly. If you have a dehydrator, do the same thing, laying the slices on the mesh racks and dry at 58-60C for 8 hours or more. Using the dehydrator, you can slice it a little thicker to give a meatier bite.
One thing you may not know about rhubarb is that the leaves will descale your kettle if you live in an area with hard water, like my home town of Whanganui. Take the leaves from a few stalks and place in the kettle with cold water to the maximum level. Bring almost to the boil and leave to cool. Bring it back almost to the boil and leave to cool again. If it needs more descaling, add fresh leaves and do the same again. Drain and rinse the kettle several times before boiling water for a cuppa as rhubarb contains oxalic acid in quite high levels — which can cause stomach upsets, kidney damage and, in extreme cases, death if taken in large quantities. Never ever eat the leaves or roots.
And if all of this is just too much, then make a fool. A perfect fool is when the sourness of the fruit pairs and contrasts in an opposing way to the creaminess of the, well, cream. Slice 500g rhubarb stalks 1cm thick, ideally nice pink ones. Put in a pan with 200g caster sugar (white sugar will keep it nice and pink), the scrapings of ½ vanilla bean and a ½ teaspoon of ground spice of your choice. I like star anise or toasted fennel.
I also love ginger with rhubarb, so add some chopped fresh ginger or stem ginger. Add 2 tablespoons lemon juice or orange juice and place over medium heat with a lid on. Slowly bring to a boil then lower the heat and cook until the rhubarb has collapsed, stirring once or twice. A few chunks make for better texture. Leave to cool completely then place in the fridge to chill. Strain the liquid from the rhubarb and reserve. Beat 400g cream with 150g Greekstyle yoghurt to medium-firm peaks and fold in half the rhubarb (or more to taste) and ½ cup rhubarb liquid. Don’t fold it in thoroughly, ripple it through. Place in the fridge and leave for an hour or so. Serve with a crisp biscuit (gingernuts are great), the reserved rhubarb and any remaining syrup. YUM.