Preheat the Oven: Preheat the oven to 425°F, and put a pot of well salted water on to boil.
Prepare the Vegetables: On a sheet pan, combine the cherry tomatoes, bell pepper, zucchini, feta, olive oil, salt, and black pepper. Toss well to coat evenly.
Roast: Roast for 30–40 minutes, until the vegetables release their juices and begin to caramelize.
Cook the Barley: While the vegetables roast, add the barley to the boiling water, and cook for about 30 minutes, or until tender. Drain and allow to cool slightly.
Combine: Transfer the roasted vegetables and feta to a large bowl. Add the cooked barley and lemon juice. Stir gently to combine.
Finish and Serve: Fold in the sliced basil. Serve warm, or refrigerate and enjoy chilled.