Preheat the oven to 120°C, fan 100°C, gas about ½.
Line a large baking sheet with baking/parchment paper.
Halve the tomatoes. I normally slice from the top to the bottom as they stay more intact.
Slice the garlic into fine slices.
Place the tomatoes into a mixing bowl with the now sliced garlic and the thyme. Add 3 tablespoons of the oil and season with sea salt and pepper.
Toss gently to coat, then arrange the tomatoes, cut-side up, on the lined baking sheets. Sprinkle over any garlic and thyme left in the bowl for added flavour. Don't want to leave any behind.
Place the tray on the middle shelf of the oven for 3 - 3½ hours or until they have reduced in size a lot.
Try one and they should be fry to the touch but still juicy in the middle.
Place the still warm tomatoes into sterilised Kilner jars and add about half a teaspoon of sherry vinegar into each jat.
Gently heat the garlic and thyme oil and pour it over the tomatoes.
Make sure the tomatoes are completely covered.
Seal the jars and store in a cool dry place for at least a few days before using.
These are gorgeous with cheese and a glass of port. (the sherry wine blends superbly)