Step 1: Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper.
Step 2: In a large bowl, toss the diced sweet potatoes, broccoli florets, and sliced bell pepper with 2 tablespoons of olive oil, a pinch of salt, and black pepper. Spread them in a single layer on the prepared baking sheet.
Step 3: Roast the vegetables for 25-30 minutes, or until tender and slightly caramelized, flipping them halfway through. Set aside to cool slightly.
Step 4: While the vegetables roast, prepare the quinoa. Combine the rinsed quinoa and vegetable broth in a medium saucepan. Bring to a boil, then reduce heat to low, cover, and simmer for 15 minutes, or until all liquid is absorbed. Remove from heat and let sit, covered, for another 5 minutes, then fluff with a fork.
Step 5: Prepare the Lemon-Herb Vinaigrette. In a small bowl, whisk together 1/4 cup olive oil, fresh lemon juice, fresh parsley, fresh dill, Dijon mustard, garlic powder, salt, and black pepper until well combined.
Step 6: In a large mixing bowl, combine the fluffed quinoa, roasted vegetables, rinsed chickpeas, and fresh spinach.
Step 7: Pour the vinaigrette over the salad ingredients. Toss gently until everything is well combined and coated with the dressing.
Step 8: Serve immediately, or refrigerate for later. Top with crumbled feta cheese before serving, if desired.