Preheat the oven to 200°C.
Heat 15ml olive oil in a 25cm ovenproof frying pan and sprinkle sugar evenly over the base.
Arrange tomatoes cut-side down in the pan, season, scatter herbs, and cook over medium heat for 10 minutes.
Cut the pastry into a circle 3cm wider than the pan.
Place pastry over tomatoes, tucking edges down the sides, and brush with beaten egg.
Bake for 20 minutes until the pastry is puffed and golden-brown.
Whisk vinegar, mustard, salt, pepper, and 75ml oil to create the salad dressing.
Flip the tart onto a large plate using oven gloves and serve warm or cold with dressed lettuce.