Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Peel and dice the sweet potato into 1-inch cubes, and cut the chicken breast into similar bite-sized pieces.
In a large mixing bowl, toss the chicken and sweet potato cubes with the olive oil, sea salt, black pepper, garlic powder, and smoked paprika until evenly coated.
Spread the mixture in a single layer on the prepared baking sheet and roast for 20-25 minutes, or until the chicken is cooked through and the potatoes are tender and browned.
While the chicken and potatoes roast, place the kale in a bowl with the lemon juice and a pinch of salt; massage with your hands for 1-2 minutes until the leaves are dark green and softened.
Thinly slice the red bell pepper and the avocado.
Assemble the bowls by dividing the massaged kale between them, then topping with the roasted chicken, sweet potatoes, and fresh bell pepper slices.
Finish each bowl with the avocado slices and serve immediately.