French onion tart with cheesy thyme pastry - Good Food Middle East

Ingredients

• 200g plain flour, plus extra for dusting
• 100g cold butter, cubed, plus 25g
• 150g gruyère, comté or vegetarian Italian-style hard cheese, grated
• small handful of thyme, leaves picked
• 1 tbsp olive oil
• 3 large onions, finely sliced
• 2 tbsp white wine or sherry vinegar
• 1 tbsp sugar
• 2 brown anchovies, finely chopped, or use 1 tsp olive tapenade or umami paste
• 2 large eggs
• 300ml double cream
• 1 tbsp extra virgin olive oil
• 2 tsp balsamic vinegar
• 2 sundried tomatoes, finely sliced
• 6-8 pitted black olives, thinly sliced
• 1 tsp capers
• a few handfuls of rocket