This recipe was originally created for Urban Harvest, do go check out their website for some great produce and other recipe ideas.
The key to this tart is taking your time with slowly, and I mean slowly caramelising the sliced onions over a low temperature, it’s not something that can be rushed, well unless you want to cheat, which I have to admit I did by using a pressure cooker, but it can be achieved in large pan on a stove on a very low flame and occasional stirring. For those who are curious and own a pressure cooker, it’s as simple as dumping the sliced onions, thyme and butter in the pot, bringing it up to high pressure and letting it cook for about 60 minutes, vent the pressure, remove the lid and then cook over a medium-low heat to evaporate off the liquid and enrich the caramelisation.
Caramelised Onions
1 kg red onions
Bunch of thyme
50 g Butter
Salt and pepper
Peel and cut the onions in half and then slice thinly, a mandoline is invaluable for this and will make quick work of it. Melt the butter in the pan over a low heat and add the onions and thyme, cover with a lid and cook very slowly, stirring occasionally. When the onions have melted down and started to colour remove the lid to allow the water to evaporate off. this could take up to an hour. Season and set aside to cool down.
An alternative method is to dump the the lot into a pressure cooker and cook on high pressure for 60 minutes, release the pressure manually. There will be a lot more liquid in the pot using this method so you will have to transfer it to a large pan (more surface area the better) and cook on a medium low heat until the water has evaporated. As above season and let cool.
Pastry
500 g white flour
250 g butter (unsalted), cubed
1/2 tsp Salt
Cold Water
It’s best to work with cold butter and work quickly when making the pastry. In a blender blitz together the flour, butter, and salt. When it forms a breadcrumb texture it is done. Tip the mix into a bowl and add about a tablespoon of cold water and start kneading it together to form a ball of dough, you may need to add more water. Wrap in cling-film and place in the fridge for at least half an hour.
Custard
4 eggs
500 ml of yoghurt
salt and white pepper
You want to mix this together right at the last minute, just after you have blind baked the pastry as you will need to steal a little egg white from the mix. Thoroughly mix together the egg and yoghurt, but take care not to incorporate too much air, season with salt and white pepper.
Assembling
Roll out the pastry to about 3mm thickness. Line a quiche tin with the pastry and trim off any excess. Place the tin in the freezer for about 15 minutes, this helps the butter to firm up and will help prevent shrinkage.
Preheat the oven to 200ºC. Remove the tin from the freezer and line the pastry with tin foil and fill up with rice (sacrificial rice sad to say, as you won't be able to eat it, but do store it so you can use it again to blind bake), cook for about 20 minutes.
Remove from the oven, and carefully remove the tin foil and rice, brush with a little egg white to seal. Place back in the oven for a couple of minutes to dry the egg white.
Remove the tin from the oven and reduce the temperature to 170ºC. Carefully make a layer of the caramelised onions and gently pour over the custard. Place back into the cooler oven and cook for 30–40 minutes, when it just starts to puff slightly near the center it is cook, it should still have a slight jiggle. Let the tart rest on the bench for 10 minutes or so, great served up with some greens dressed simply with lemon juice.
