Prep the chicken: Pat chicken dry. If using breasts, slice horizontally to create thin cutlets for even cooking.
Make the marinade: In a bowl, combine lemon zest, lemon juice, garlic, olive oil, parsley, salt, pepper, smoked paprika, and red pepper flakes.
Marinate: Add chicken to the bowl and toss to coat.
Chill for at least 30 minutes, up to 8 hours. Do not marinate overnight; too much acid can make the texture mushy.
Prep the veggies: Toss broccoli, bell pepper, onion, and tomatoes with olive oil, salt, and pepper.
Roast the veggies: Spread on a sheet pan and roast at 425°F (220°C) for 15–20 minutes, until crisp-tender with a little char.
Cook the chicken: Heat a large skillet over medium-high. Sear chicken 4–5 minutes per side (thighs may need a bit longer) until cooked through and browned. Internal temp should reach 165°F (74°C).
Rest and slice: Let chicken rest 5 minutes, then slice against the grain.
Squeeze extra lemon over the top.
Assemble: Divide chicken, veggies, and your carb of choice into 4–5 meal prep containers. Add a light drizzle of olive oil and a pinch of flaky salt.