Preheat and prep: Heat your oven to 425°F (220°C). Line a large baking sheet with parchment for easier cleanup.
Pat the chicken dry with paper towels.
Mix the lemon-herb marinade: In a bowl, combine olive oil, lemon zest, lemon juice, garlic, salt, pepper, thyme, rosemary, and smoked paprika if using. Stir to make a loose paste.
Season the chicken: Add the chicken to the bowl and coat well. Let it sit while you prep the vegetables (5–10 minutes is enough for quick flavor absorption).
Prep the vegetables: In a separate bowl, toss potatoes, broccoli, bell pepper, and red onion with a drizzle of olive oil and a pinch of salt and pepper.
Keep it light—extra oil can make the pan steamy instead of crisp.
Arrange on the pan: Spread the vegetables into an even layer with some space between pieces. Nestle the chicken among the vegetables, making sure nothing overlaps too much.
Roast: Place in the oven and cook for 25–35 minutes. Chicken thighs usually take around 28–32 minutes; breasts can be done a bit sooner. Stir the vegetables once halfway through for even browning.
Check doneness: The chicken is ready when the internal temperature hits 165°F (74°C) and the juices run clear.
Potatoes should be tender when pierced with a fork, and edges of vegetables lightly charred.
Finish and rest: Remove the pan and let the chicken rest for 5 minutes. Sprinkle with chopped parsley and an extra squeeze of lemon if you like.
Serve: Plate the chicken with a generous scoop of vegetables. Spoon any pan juices over the top for extra flavor.