Makes approx. 40.
Preheat oven to 200°C.
Cut the tomatoes in half horizontally. Arrange them, cut side up on a baking tray so that they are touching each other and spread their surfaces with a little Balsamic Mustard. Drizzle the olive oil over them.
Put them at the top of the oven for 5 minutes then turn it off. Leave in the oven until it has cooled down (between 1½ -2 hours) without opening the oven door.
Slice the baguette or ficelle into rounds approx. ½cm thick and lightly toast under the grill. Spread with a little more Balsamic Mustard and top with a slice of mozzarella and an oven dried balsamic tomato.
Warm under a grill for 2 mins prior to serving.