Heat the oven: Preheat to 425°F (220°C). Line two baking sheets with parchment for easy cleanup.
Prep the vegetables: Add peppers, onion, zucchini, eggplant, tomatoes, and broccoli to a large bowl.
Toss with 2 tablespoons olive oil, salt, pepper, paprika, oregano, and red pepper flakes if using.
Roast: Spread veggies in a single layer on the sheets. Roast 20–25 minutes, tossing halfway, until the edges are browned and the centers are tender.
Cook the quinoa: Rinse quinoa under cold water until it runs clear. Combine quinoa and water (or broth) in a saucepan.
Bring to a boil, reduce to a low simmer, cover, and cook 15 minutes. Remove from heat and let sit 5 minutes, then fluff with a fork.
Toast the chickpeas (optional but tasty): Toss chickpeas with the remaining 1 tablespoon olive oil, a pinch of salt, and paprika. Spread on a small section of the baking sheet for the last 10–12 minutes of roasting to crisp slightly.
Make the dressing: Whisk lemon zest, lemon juice, garlic, Dijon, and maple syrup.
Slowly whisk in olive oil until emulsified. Season with salt and pepper.
Assemble the salad: In a large bowl, combine quinoa, roasted vegetables, chickpeas, and parsley. Pour over the dressing and toss until evenly coated.
Finish and serve: Taste and adjust salt, pepper, or lemon.
Sprinkle with feta if using. Serve warm or at room temperature.