Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Prepare the vegetables by trimming and halving the Brussels sprouts, slicing the carrots into thin coins, and roughly chopping the red onion.
Slice the chicken breast into even 1-inch strips to ensure they cook at the same rate as the vegetables.
In a small mixing bowl, whisk together the extra virgin olive oil, lemon juice, minced garlic, rosemary, thyme, sea salt, and black pepper.
Place the chicken and all the vegetables onto the prepared baking sheet, pour the lemon-herb dressing over them, and toss thoroughly to coat every piece.
Spread the mixture out into a single layer, ensuring nothing is overcrowded, and roast for 20 to 25 minutes until the chicken is golden and the vegetables are tender.