Caramelised Onion Tart

My first blog post of 2022! With plenty of food still to use up from Christmas I thought I’d kick off with a recipe utilising just store cupboard ingredients. Caramelised Onion Tart, simple as it is, ticks all the boxes on flavour. Buttery, sweet onions cooked slowly with a few cloves of garlic until meltingly tender, sticky and golden in colour. Combined with wholegrain mustard and an egg custard enriched with crème fraîche is possibly my new favourite tart.

The pastry; a simple, flaky, butter shortcrust. I like to use wholemeal and white spelt flour. Also, instead of adding water or egg to the pastry, in this recipe I have used Greek-style yogurt, resulting in a lighter, crisp yet crumbly texture. Chilling the pastry before baking will inhibit shrinkage and baking blind is essential, a good 20 minutes in the oven will prevent a soggy bottom.

Honestly, you’ll want to add this simple Caramelised Onion Tart to your meat free dinner rotation or try this Cauliflower Cheese Tart with a salad and possibly some air fryer French fries this winter. A glass of Austrian riesling works well with it, entirely optional of course! Then enjoy what’s left for lunch the next day. Happy days!

This tart freezes well for up to 3 months.  Defrost naturally and warm through in the oven 160°C fan for 10-15 minutes.  If you follow mean on Instagram, you can find a ‘How to’ video in highlights.

Print Recipe

Caramelised Onion Tart

Prep Time35 minutes mins

Cook Time1 hour hr 20 minutes mins

Total Time1 hour hr 55 minutes mins

Course: Lunch/Dinner, Main Course

Keyword: seasonal,, vegetarian,

Servings: 6 people

Equipment

• 25cm Tart tin

Ingredients

• 1 kg brown onions peeled & sliced
• 40 g butter
• 1 tbls olive oil
• 100 g crème fraîche
• 90 ml milk
• 1 egg
• 1 egg yolk
• 1.5 Tbls wholegrain mustard
• 1 tbls chopped herbs ie. thyme or chives
• 1 tbls grated mature cheese ie. cheddar or Parmesan

Pastry

• 100 g wholemeal spelt flour
• 80 g white spelt flour
• 80 g cold butter diced
• 60 g Greek-style yogurt full fat

Instructions

• Preheat the oven to 180°C fan.
• Begin with slicing the onions, use a mandoline if you have one. Heating the butter and oil in a pan and cook the onions and garlic for 45-60 mins, stirring occasionally on high at first, then reduce the heat to very low, cover with a lid. Cook until they become sticky and golden. Remove from the heat and cool to room temperature.
• To make the pastry, tip the flour and butter into a bowl, add a pinch of salt then rub together with your fingertips until completely mixed and crumbly. Add the Greek yogurt, then bring everything together with your hands until just combined. Roll into a ball and chill for 30 minutes.
• Lightly grease the base of the tart tin. Roll out the pastry on a lightly floured surface to approximately 5cm larger than a 25cm tin. Use your rolling pin to lift it up, then drape over the tart case so there is an overhang of pastry on the sides. Using your fingers to push the pastry into the corners of the tin. With you fingertips pinch off the excess pastry. Chill in the fridge for 15-20 minutes.
• Increase the oven temperature to 190°Cfan.
• Lightly prick the base of the tart with a fork, line the tart case with a large circle of greaseproof paper or foil, then fill with baking beans. Blind-bake the tart for 10 mins, remove the paper and beans, then continue to cook for 10-12 minutes until biscuit brown.
• Whisk the egg and egg yolk with the crème fraîche and milk. Add the wholegrain mustard and cooled onions. Season with salt and pepper. Pour into the pastry case and sprinkle with fresh herbs. Bake for 22-25 minutes or until golden and set. Serve warm sprinkled with grated cheese (optional) with a bitter leaf salad.

Tips:

Optional extras if you’re not wanting meat-free are;

• anchovies, add 8-10 fillets, chop half and add to the mixture.  Arrange the remainder on the top. Cut back on the seasoning though
• 90g bacon lardons, fried until crisp, cooled and stirred through the filling, also cut back on the seasoning