Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Dice the eggplant, zucchini, and red bell pepper into uniform half-inch cubes to ensure even roasting.
Slice the chicken breast into thin strips and season evenly with sea salt, black pepper, and dried oregano.
Toss the diced vegetables with half of the olive oil and spread them in a single layer on one side of the baking sheet.
Place the seasoned chicken strips on the other side of the baking sheet and roast for 18 to 20 minutes until the chicken is cooked through and the vegetables are tender.
While the sheet pan is in the oven, sauté the diced yellow onion and minced garlic in the remaining olive oil in a small saucepan over medium heat until translucent.
Stir in the tomato puree and simmer the sauce on low heat for about 5 minutes to allow the flavors to meld.
Once roasted, combine the vegetables and chicken with the warm tomato sauce in a large bowl and toss gently.
Garnish the dish with freshly torn basil leaves before serving warm.