Preheat your oven to 400°F (200°C).
Peel and cube the sweet potato, chop the bell pepper, and slice the zucchini into half-moons.
On a large parchment-lined baking sheet, toss the sweet potato, bell pepper, and zucchini with 0.5 tbsp of olive oil, dried oregano, and half of the salt and pepper.
Season the chicken breast with the remaining salt and pepper and place it on the baking sheet alongside the vegetables.
Roast for 20 to 25 minutes until the vegetables are tender and the chicken reaches an internal temperature of 165°F.
Remove from the oven and let the chicken rest for 5 minutes before slicing it into thin strips.
In a large salad bowl, whisk together the remaining 0.5 tbsp of olive oil and the lemon juice to create a simple vinaigrette.
Add the arugula to the bowl and toss thoroughly to coat the leaves.
Arrange the roasted vegetables and sliced chicken over the arugula and serve immediately.