Cook the grain: Make quinoa or brown rice according to package directions.
Fluff and set aside. A squeeze of lemon and pinch of salt at the end brightens the flavor.
Preheat and prep: Heat the oven to 425°F (220°C). Line a large sheet pan with parchment for easy cleanup.
Season the chicken: Pat chicken dry.
Toss with 1 tbsp olive oil, smoked paprika, garlic powder, cumin, oregano, salt, and pepper. Add a squeeze of lemon.
Season the veggies: On the sheet pan, toss broccoli, bell pepper, and zucchini with 1 tbsp olive oil, salt, and pepper. Spread everything in a single layer.
Add the chicken to the same pan, leaving space around each piece.
Roast: Roast for 18–22 minutes, flipping the chicken once halfway. The chicken is done when the internal temperature hits 165°F (74°C) and juices run clear. Add cherry tomatoes for the last 6–8 minutes so they blister without collapsing.
Make the sauce: In a small bowl, whisk Greek yogurt, olive oil, garlic, lemon juice and zest, honey (if using), salt, pepper, and herbs.
Adjust to taste. It should be tangy and a little garlicky.
Slice the chicken: Let the chicken rest for 5 minutes, then slice or cube.
Assemble: In bowls, add a base of greens and warm grains. Top with roasted veggies, chicken, avocado, and tomatoes.
Spoon over the yogurt sauce.
Add crunch and finish: Sprinkle with pumpkin seeds or almonds, a pinch of red pepper flakes, and crumbled feta if you like. Add a final squeeze of lemon and a crack of black pepper.