Halve the tomatoes across and lay on baking trays.
Sprinkle with chopped assorted fresh herbs.
Mix together the castor sugar, a pinch of salt and some coarse black pepper and sprinkle over the tomatoes.
Drizzle over the olive oil and balsamic vinegar and bake for approximately 1-1/2 hours in preheated oven 120C/Gas mark 1/2 until wrinkling slightly and caramelising.
Turn off oven and leave the tomatoes in the oven until cold.