Bring the broth to a boil in a small saucepan. Stir in the couscous, cover, and remove from the heat.Let sit for 5 minutes, then fluff with a fork. Transfer couscous to a large bowl and let it cool slightly.
Halve the cherry tomatoes, dice the cucumber, finely dice the red onion, and chop the fresh herbs.
In a small bowl or jar, whisk together olive oil, balsamic vinegar, lemon juice, lemon zest, Dijon mustard, garlic, oregano, salt, and pepper until well combined.
Add tomatoes, cucumber, red onion, parsley, dill, mint, chickpeas, and feta to the bowl with the couscous.Pour the vinaigrette over the salad and toss gently until everything is evenly coated.
Serve right away, or refrigerate for 20–30 minutes to let the flavors blend.Taste before serving and adjust seasoning with additional lemon juice, salt, pepper, or herbs if needed.