Preheat your oven to 425°F. Line a large rimmed sheet pan with parchment paper for easy cleanup (trust me on this one).
In a large bowl, whisk together the olive oil, lemon juice, garlic, oregano, thyme, salt, pepper, and paprika.
Add the chicken chunks to the bowl and toss to coat. Let them sit while you prep the vegetables — even 10 minutes of marinating helps.
Add the potatoes, broccoli, bell pepper, and onion to the same bowl. Toss everything together until the vegetables are coated in the lemon-herb mixture.
Spread everything in a single layer on the sheet pan. This matters — if the pan is crowded, the vegetables steam instead of roast. Use two pans if needed.
Roast for 22-25 minutes, flipping the chicken and vegetables halfway through, until the chicken reaches 165°F internally (USDA safe temp) and the potatoes are golden and fork-tender.
Squeeze fresh lemon over everything and shower with parsley before serving.