Preheat the oven to 350F (180C).
For the tomatoes: Spread the tomatoes out on a large baking sheet and drizzle with 1 tablespoon olive oil, and season with a bit of salt and pepper. Toss to coat. Roast in the oven for 35 minutes until soft.
For the barley: prepare the barley by placing it in a sieve and rinsing it under cold running water. Place the barley into a saucepan and cover with water until 1-inch (5cm) above the barley. Bring to the boil then reduce the heat to low and allow to simmer uncovered for 35 minutes until tender and cooked through. Drain and set aside.
For the Spicy Chickpea Croutons: Spread the chickpeas out on baking tray. Toss them with Sriracha. Place the tray into the oven and bake the chickpeas for the last 10 minutes of the tomato cooking time.
For the Soup: When the tomatoes are done roasting, heat 1 tablespoon of olive oil in a large soup pot over medium-high heat. Add the onion and garlic and sauté until the onions turn translucent and begin to brown, about 5 minutes. Add the thyme leaves and sauté 1 minute more. Pour in the vegetable broth and add about 1⁄4 of the roasted tomatoes.
Place the remaining tomatoes into a blender and blitz to smooth and pour into the soup. Add in the drained barley, chopped parsley, sugar, and season with salt and black pepper to taste. Mix well to combine, bring to a boil and turn the heat down and allow to simmer gently for 5 minutes. Serve the soup in bowls, topped with chickpea croutons.