Recipe here (slight warning: although the recipe for these tomatoes is vegan, I do suggest some uses for them that are vegetarian rather than vegan)
300g cherry tomatoes
3tbsp olive oil
2tbsp balsamic vinegar
Salt, to taste
Preheat the oven to 150°C (Gas Mark 2 / 300°F). Toss the tomatoes in the olive oil and balsamic, and lay them out in a single layer on a baking tray. Sprinkle with salt. Roast for around 2 1/2 hours - the timing doesn't need to be at all precise, so just take them out whenever you are ready.