Inexpensive and ubiquitous, the brown onion is a kitchen workhorse, pressed into service for everything from hamburgers to stews, stir-fries or curries. Seldom does it get a chance to star as it does in this recipe—a classic provincial onion tart of the kind made famous beyond France by Elizabeth David’s French Provincial Cooking. The beauty of it is that almost all the ingredients are the kinds of things you’ll have lurking in the pantry or fridge—and if not, there’s nothing you shouldn’t be able to grab from a corner store or servo. The result, however, is anything but run-of-the-mill, smart enough to serve guests for lunch alongside a green salad and relish or chutney.
The key to success lies in ensuring the onions are slowly cooked, soft and sweet; Generally, this means cooking in a heavy-based pot watching always to make sure they don’t catch or brown; the Thermomix solves that issue. Pop them in for half an hour and have a nap: just make sure the Thermomix is cooking away on the back porch or in the laundry, otherwise the whole house will be in tears, and not from a soppy movie.
If you’ve made our Maggie Beer-inspired sour cream pastry ahead of time, it’s then the work of mere seconds in the Thermomix to blend the creamy, eggy filling. Lesley advises resisting the temptation to add cheese (“then it becomes just another generic quiche”) and allowing the flavour of the tender, translucent onions to shine through.
The tart is delicious at room temperature as well as warm, but will reheat beautifully if required.
- Peel and halve the onions then slice them as finely as you can.
- Place them into the Thermomix bowl with the olive oil and allow them to cook away 30–35 minutes/100 degrees/reverse/speed 2 MC off. Once they are cooked, transfer the onions to a mixing bowl and allow them to stand until they are cold. This step can be done well in advance. Some onions produce large amounts of liquid so if this is the case, drain them through a colander. Don’t throw out the juice though, stir it into something else such as soup.
- Meanwhile, heat the oven to 180C fan-forced and place a solid baking tray that won’t buckle on the centre shelf. This provides base heat which helps to crisp the pastry. Grease a 22-centimetre round springform tin.
- Roll out the pastry until it is quite thin, about 3 millimetres. Line the greased tin with the pastry. An easy way to do this it to fold the rolled-out pastry into four quadrants then gently lift it and align the apex with the centre of the tin. Then, supporting the pastry with your hands, unfold it again, easing it down into the tin. Press the dough into the corners and up on the sides of the tin, if it creases here and there don’t worry, just press it together firmly.
- The pastry will be too large for the tin and there will be quite a bit of overhang but this is trimmed off after the pastry has been baked, creating a nice neat edge. Prick the base of the pastry with a fork here and there. If it all looks a bit rough on the inside, don’t worry, only the outside will be seen in the end anyway.
- Scrunch up a piece of baking paper—if you wet the paper this will be much easier—and line the un-baked shell with it. Fill with rice and bake the pastry shell on top of the hot tray in the centre of the oven for 20 minutes.
- Remove the paper and rice and carefully trim the edge of the pastry with a sharp knife so it is level with the top of the tin. Return to the oven and allow the base to cook further and dry out.
- Turn oven down to 170C.
- Add the eggs, cream, salt and pepper to the Thermomix bowl. Mix 5 seconds/speed 5.
- Add the onions—there should be 500 grams cooked weight—and mix together 3 seconds/reverse/speed 2. Pour the onion filling into the blind-baked shell.
- Place the tart back into the oven and cook for 45 minutes or until set in the centre and nicely browned.
- Allow to cool for 15 minutes before removing from the tin. Serve the tart cut into wedges.