Onion tart with caraway and a green salad

Serves - 4

You’ll need

• 1 sheet all-butter puff pastry
• 3 large onions, finely sliced
• 2 tbsp olive oil
• 25g butter
• 1 tsp caraway seeds
• 2 tbsp crème fraîche
• 1 tsp Dijon mustard
• 100g Gruyère, Comté or vegetarian hard cheese, finely grated
• 1 egg, beaten
• Sea salt
• Black pepper

For the green salad
• 1 little gem lettuce, or a few handfuls of mixed leaves
• 1 small shallot, very finely sliced
• 2 tbsp extra virgin olive oil
• 1 tbsp white wine vinegar or lemon juice
• Sea salt
• Black pepper

Method

1. Get the onions going

Heat the olive oil and butter in a large frying pan over a medium-low heat. Add the sliced onions with a good pinch of salt and cook gently for 20–25 minutes, stirring now and then, until soft, golden and properly collapsed. This is not the bit to rush. You want sweetness and depth, not onions that have merely warmed through and called it a day.

2. Add the caraway

Stir the caraway seeds into the onions and cook for another minute or two, just until fragrant. Give everything a good grind of black pepper, then take the pan off the heat and leave it to cool slightly.

3. Get the pastry ready

Heat the oven to 200°C fan. Unroll the puff pastry onto a lined baking tray and score a border about 2cm in from the edge, being careful not to cut all the way through. This gives you that nicely puffed frame around the tart rather than something flat and a bit sorry for itself.

4. Build the base

Mix the crème fraîche with the Dijon mustard, then spread it over the middle of the pastry, staying within the border. Scatter over half the grated cheese, then spoon the onions evenly over the top. Finish with the rest of the cheese.

5. Bake until golden

Brush the pastry border with the beaten egg, then bake for 25–30 minutes until the pastry is puffed and bronzed and the topping is golden in places. You want crisp edges and a tart that looks as though it knows exactly what it is doing.

6. Make the salad

While the tart bakes, whisk together the extra virgin olive oil, white wine vinegar or lemon juice, a pinch of salt and a good grind of black pepper. Add the shallot and leave it for a few minutes so it softens slightly and loses any unnecessary sharpness.

7. Serve

Toss the lettuce or mixed leaves in the dressing just before serving. Leave the tart to sit for 5 minutes once out of the oven, then slice and serve with the green salad alongside. Very good while still warm, and no less welcome at room temperature.

A couple of helpful notes
- If the onions look as though they are catching too quickly, turn the heat down and add a tiny splash of water rather than pretending they will sort themselves out.
- Gruyère is particularly good here, but any nutty hard cheese with a bit of savoury depth will do nicely.
- A few thyme leaves scattered over the tart before baking would not hurt at all if you want to push it in a slightly more fragrant direction.