01 - Rinse the quinoa thoroughly under cold running water until water runs clear.
02 - Combine quinoa and vegetable broth in a medium saucepan. Bring to a boil over high heat, then reduce to low, cover, and simmer for 15 minutes until liquid is absorbed. Remove from heat and let stand covered for 5 minutes. Fluff with a fork.
03 - Heat 1 tablespoon olive oil in a large skillet over medium heat. Add chopped red onion and sauté for 2 minutes until translucent.
04 - Add diced bell pepper and zucchini to the skillet. Cook for 4-5 minutes until softened and edges begin to brown.
05 - Stir in halved cherry tomatoes and cook for 2 minutes until skins blister. Add baby spinach and sauté until wilted, about 1 minute.
06 - In a small bowl, whisk together lemon juice, lemon zest, 1 tablespoon olive oil, minced garlic, ground cumin, salt, and black pepper until emulsified.
07 - Add cooked quinoa to the skillet with vegetables. Pour the dressing over the mixture and toss gently to combine evenly.
08 - Remove from heat. Garnish with chopped parsley and crumbled feta cheese if desired. Serve immediately while warm.