Preheat oven to 400°F (200°C). Toss chickpeas with 1 tablespoon olive oil and ¼ teaspoon cumin. Roast for 20-25 minutes, or until crispy.

In a large pot or Dutch oven, heat 2 tablespoons olive oil over medium heat. Add onion and cook until softened, about 5 minutes.

Add carrots, garlic, coriander, cumin, and salt. Cook for another 5 minutes, stirring occasionally.

Pour in vegetable broth and bring to a boil. Reduce heat and simmer for 20-25 minutes, or until carrots are tender.

While the soup simmers, prepare the tahini sauce: In a small bowl, whisk together tahini, lemon juice, and a pinch of salt. Add water, 1 tablespoon at a time, until the sauce reaches your desired consistency.

Carefully transfer the soup to a blender (or use an immersion blender) and blend until smooth.

Serve the soup with a drizzle of tahini sauce and a sprinkle of roasted chickpeas. Garnish with parsley, if desired.