Start by rinsing the barley under cold water until the water runs clear.
In a large pot, bring 3 cups (720 ml) of water to a boil. Add a pinch of salt.
Pour the rinsed barley into the boiling water.
Reduce the heat, cover, and simmer for 30 minutes.
While the barley is cooking, preheat your oven to 425°F (220°C).
Toss the chopped bell peppers, zucchini, carrots, and red onion in a bowl with olive oil. Season with salt and pepper.
Spread the vegetables on a baking tray in a single layer.
Roast the vegetables in the preheated oven for about 20 minutes, or until tender and slightly caramelized.
In a small bowl, whisk together the lemon juice, balsamic vinegar, and honey to make the dressing.
Once the barley is cooked, drain any excess water and transfer to a large mixing bowl.
Add the roasted vegetables to the barley.
Drizzle with the dressing and toss everything together.
Garnish with fresh parsley before serving.