Heat the oven to 150°C/300°F. Put the halved tomatoes on a baking sheet and toss with the olive oil, sugar, garlic, thyme and plenty of salt and pepper. Roast for 1 ½ hours until caramelised.
While the tomatoes roast cook the barley according to packet instructions and leave to cool. Whisk together all of the dressing ingredients and set aside until ready to use.
When the tomatoes are ready add them to the bowl with the barley and toss together. Sprinkle in the feta, pine nuts and herbs and toss well. Add the dressing and toss again.
Prepare ahead: The tomatoes can be roasted and the pearl barley cook ahead of time and stored in the fridge for a couple of days until ready to use.Nutrition information is an estimate and will vary depending on the exact ingredients used.