Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Place the chicken breast, cubed sweet potato, and halved Brussels sprouts on the baking sheet.
Drizzle with the olive oil and sprinkle with sea salt, black pepper, and garlic powder, tossing well to coat evenly.
Roast for 20-25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and caramelized.
While the chicken roasts, whisk together the tahini, lemon juice, Dijon mustard, and water in a small bowl until the dressing is smooth and pourable.
Place the chopped kale in a large mixing bowl with a tiny pinch of salt and massage the leaves with your hands for 1-2 minutes until they become dark green and tender.
Slice the roasted chicken into strips and add it to the bowl along with the roasted sweet potatoes and Brussels sprouts.
Top the salad with sliced avocado and pumpkin seeds, then drizzle the lemon-tahini dressing over the top and toss gently before serving.