01 - Preheat oven to 400°F.
02 - Toss sweet potato cubes and red onion slices with 1 tablespoon olive oil, salt, and pepper. Spread on a baking sheet in a single layer. Roast for 20–25 minutes, stirring halfway, until sweet potatoes are tender and slightly caramelized.
03 - While vegetables roast, combine quinoa and water in a saucepan. Bring to a boil, cover, reduce heat, and simmer for 15 minutes or until water is absorbed. Remove from heat and let stand, covered, for 5 minutes. Fluff with a fork.
04 - In a large bowl, whisk together remaining olive oil, lemon juice, garlic, Dijon mustard, ground cumin, salt, and pepper.
05 - Add cooked quinoa, roasted sweet potato, red onion, bell pepper, cherry tomatoes, parsley, and baby spinach to the bowl with dressing. Toss gently to combine.
06 - Taste and adjust seasoning as needed. Transfer to serving plates. Top with crumbled feta and pumpkin seeds, if using. Serve warm.