Cook the quinoa: Rinse quinoa under cold water. Combine 1 cup quinoa with 2 cups water (or broth) and a pinch of salt in a pot. Bring to a boil, cover, and simmer on low for 15 minutes. Turn off heat, let it sit covered for 5 minutes, then fluff with a fork.
Roast the vegetables: Preheat oven to 400°F (200°C). Place zucchini, peppers, onion, and tomatoes on a baking sheet. Drizzle with olive oil, sprinkle oregano, paprika, salt, and pepper. Toss well. Roast for 20–25 minutes, stirring once, until tender and caramelized at the edges.
Make the dressing: In a small bowl, whisk olive oil, lemon juice, vinegar, garlic, mustard, basil, salt, and pepper until smooth.
Assemble the salad: In a large bowl, mix cooked quinoa and roasted vegetables. Pour dressing on top and toss gently. Add feta, olives, and herbs if using.
Serve: Enjoy warm, at room temperature, or chilled straight from the fridge.