Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.
Toss zucchini, pepper, carrots, and onion with 2 tbsp olive oil, salt, and pepper. Roast 20–25 minutes.
Cook pasta in boiling water for 10 minutes. Drain and rinse.
Cook quinoa according to package instructions, about 15 minutes. Fluff with fork.
In a small bowl, whisk lemon juice, garlic, and 1 tbsp olive oil.
In a large bowl, combine pasta, quinoa, roasted vegetables, and dressing.
Toss well and garnish with parsley. Serve warm or chilled.
