Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper.
Dice the chicken breast, eggplant, zucchini, and red bell pepper into uniform 1-inch cubes.
In a large mixing bowl, combine the chicken and chopped vegetables with olive oil, dried oregano, garlic powder, sea salt, and black pepper.
Toss everything thoroughly until the chicken and vegetables are evenly coated in the oil and spices.
Spread the mixture in a single layer on the prepared baking sheet, ensuring space between pieces for optimal roasting.
Roast in the center of the oven for 20 minutes, or until the chicken is cooked through and the vegetables are tender and slightly caramelized.
Remove the tray from the oven, pour the tomato puree and lemon juice over the mixture, and stir gently to combine.
Return the tray to the oven for an additional 5 minutes to allow the sauce to thicken and the flavors to meld.
Garnish with freshly chopped basil and serve warm.