Bring a large pot of generously salted water to a boil. Add the carrots and cook until just tender when pierced with the tip of a knife, 15 to 20 minutes. Drain well and let cool until easy to handle.
Cut the carrots into thick rounds or bite-size pieces and transfer to a large serving bowl.
In a small bowl, whisk together the harissa, preserved lemon, olive oil, vinegar, lemon juice, cumin, sugar, salt, and black pepper until smooth.
Add the parsley, cilantro, and garlic to the carrots. Pour the dressing over the top and gently toss until evenly coated.
Refrigerate for at least 30 minutes before serving to allow the flavors to meld. Taste and adjust the seasoning with additional salt or lemon juice, if needed. Serve chilled or at room temperature.