BBC Food - Recipes - Heritage tomato tart with blow-torched tomato salad

Ingredients

• 400g/14oz ready-made all-butter puff pastry
• plain flour , for dusting
• 1 free-range egg yolk , beaten
• 200g/7oz Gruyère , grated
• 400g/14oz mixed heritage tomatoes , thickly sliced
• 4 sprigs fresh thyme , leaves only
• 1 tbsp rapeseed oil
• salt and freshly ground black pepper
• 300g/10½oz heritage tomatoes
• 1 red onion , thickly sliced
• 2 heads Romaine lettuce , roots removed, cut into thick slices
• 4 tbsp vegetable oil
• 1 tbsp white wine vinegar
• 1 tbsp Dijon mustard
• 1 egg yolk