Preheat the oven to 160C/gas 3/fan
140C. Put a griddle pan or heavy cast
iron frying pan (not non-stick) over a high
flame and leave it to heat.
Cut the tomatoes in half around the
equator. Brush the cut surfaces with 1 tbsp
of oil and place cut side-down on the hot
griddle. Cook undisturbed for 1 minute,
then take the pan off the heat.
Transfer the tomatoes, cut side-up, to a
shallow baking dish. Brush cut surfaces
with the vinegar, then with about 2 tbsp of
oil. Place a sliver or two of garlic on each
tomato, and sprinkle with the sugar.
Bake for about 1 hour until the tomatoes
are deep brown and sticky-looking. Cool a
little, then finish with a sprinkling of balsamic
vinegar, extra oil and a scattering of basil.
Serve warm or at room temperature.