Preheat your oven to 400°F and line a baking sheet with parchment paper.
Peel and chop the carrots and parsnips into 1-inch bite-sized pieces.
Place the chicken breast, carrots, and parsnips onto the prepared baking sheet.
Drizzle everything with olive oil and season evenly with the dried thyme, rosemary, garlic powder, sea salt, and black pepper.
Roast in the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the root vegetables are tender.
While the chicken is roasting, combine the green lentils and water in a small saucepan and bring to a boil.
Reduce the heat to low, cover the pan, and simmer for 15 to 20 minutes until the lentils are tender but still hold their shape.
Drain any excess liquid from the lentils and spread them onto a serving plate.
Slice the roasted chicken breast and arrange it over the lentils along with the roasted root vegetables.
Top the dish with fresh avocado slices and serve immediately.