Preheat the oven. Set it to 425°F (220°C). A hot oven helps caramelize sweet potatoes and gives chicken a nice color.
Prep the sweet potatoes. Toss the cubes with 1–1.5 tablespoons olive oil and 1/2 teaspoon salt. Spread on a large sheet pan in a single layer.
Start roasting the potatoes. Bake for 12–15 minutes to give them a head start.
They take longer than the chicken and veggies.
Season the chicken. Pat dry. In a bowl, mix smoked paprika, garlic powder, onion powder, oregano, cumin, black pepper, and 1/2–3/4 teaspoon salt. Add 1 tablespoon olive oil and toss to coat the chicken evenly.
Zest half the lemon over the chicken for a bright lift.
Prep the vegetables. In another bowl, toss onion, bell pepper, and broccoli with 1 tablespoon olive oil, a pinch of salt, and chili flakes if using.
Add everything to the pan. Pull the sweet potatoes from the oven. Push them to one side. Add chicken and vegetables to the open space, keeping items in loose, even layers for good browning.
Roast until done. Return the pan to the oven for 15–18 minutes.
Chicken is done at an internal temperature of 165°F (74°C). Veggies should be tender with a little char at the edges.
Rest and finish. Let the chicken rest on the pan for 5 minutes. Squeeze the lemon juice over everything and sprinkle with chopped herbs.
Make the sauce. Stir together Greek yogurt, lemon juice, honey, grated garlic, salt, and pepper.
Thin with a teaspoon of water if you want a drizzleable consistency.
Portion. Divide the sweet potatoes, vegetables, and chicken into 4–6 containers. Add a spoonful of sauce to each or pack it separately if you prefer.