Pickled tomato salad recipe - Telegraph You need fibrous, small plum tomatoes to make this dish, which can be eaten on thick slices of baguette, or served as a salad with a little cheese. 2 red onions, halved and sliced 2 tbsp Demerara sugar 2 tbsp balsamic vinegar Preheat the oven to 220C/gas mark 7. Put the tomatoes in a colander and squeeze them to remove most of the juice and pips. Place them on a roasting tray, brush with half the olive oil and put in the oven. Bake until the edges of the tomatoes are lightly roasted, remove from the oven and leave to cool. Meanwhile put the sliced red onion in a pan with the rest of the olive oil and cook over a low heat until soft. Add the sugar and vinegar and allow to simmer until syrupy. Put in a bowl with the tomatoes and mix well before serving.