Rinse quinoa thoroughly using a fine-mesh sieve under cold running water for at least 30 seconds.
In a medium saucepan, combine rinsed quinoa and vegetable broth or water and bring to a boil over medium-high heat.
Once boiling, reduce heat to low, cover with a tight-fitting lid, and simmer for 15 minutes without lifting the lid.
Remove from heat and let the quinoa sit, covered, for an additional 5 to 10 minutes to steam.
Fluff quinoa gently with a fork and let cool slightly.
Meanwhile, finely chop parsley, mint, and dill, and thinly slice green onions; prepare optional vegetables if using.
Rinse and drain chickpeas; optionally remove skins for creamier texture.
In a small bowl or jar, whisk or shake together olive oil, lemon juice, lemon zest, minced garlic, red pepper flakes, sea salt, and black pepper until well combined.
In a large bowl, combine cooled quinoa, chickpeas, herbs, green onions, and optional vegetables.
Pour the lemon herb dressing over the mixture and gently toss to coat evenly without mashing the quinoa.
Taste and adjust seasoning with extra salt, pepper, or lemon juice as desired.
For best flavor, let the dish rest covered at room temperature for 15-20 minutes or chill for 30 minutes to an hour.
Serve warm, room temperature, or chilled, garnished with optional feta cheese, Kalamata olives, or fresh herb sprigs.