Add the barley to simmering water, reduce the heat, simmer for approx. 25 mins until just soft, drain.
Mix the vegetables, oil and salt, spread onto a baking tray lined with baking paper. Bake for approx. 20 mins. in the centre of an oven preheated to 220°C. Remove and allow to cool a little.
Mix the vinegar, oil, salt and pepper in a large bowl. Add the barley and roasted vegetables, mix.