Preheat your oven to 425°F (220°C) and line a large sheet pan with parchment paper.
Pat the chicken thighs extremely dry with paper towels to ensure the skin gets maximum crispiness during roasting.
Trim the Brussels sprouts and halve them, and slice the carrots into half-inch rounds.
In a large bowl, toss the Brussels sprouts and carrots with half of the olive oil, sea salt, and black pepper.
In a small ramekin, combine the remaining olive oil, minced garlic, chopped rosemary, thyme, and the zest of the half lemon.
Rub the herb and oil mixture thoroughly over and under the skin of the chicken thighs.
Arrange the chicken and vegetables in a single layer on the prepared sheet pan, ensuring they are not overcrowded.
Roast for 25 to 30 minutes, or until the chicken reaches an internal temperature of 165°F and the skin is deeply bronzed.
Remove from the oven and immediately squeeze the fresh lemon juice over the chicken and vegetables before serving.