Rinse the quinoa under cold water to remove any bitterness, then cook it according to package directions (typically 1:2 ratio of quinoa to water, about 15 minutes). Once cooked, spread it on a baking sheet or plate to cool completely—this prevents the salad from becoming warm and wilted. While the quinoa cools, you can proceed with your other prep work.

Dice the celery into uniform 1/4-inch pieces to ensure consistent crunch throughout the salad. Dice the tomatoes into similar-sized pieces, removing excess seeds if they're very watery to prevent the salad from becoming soggy. Finely mince the garlic clove and onion so the flavors distribute evenly without overpowering bites. Roughly chop the fresh dill, mint, and chives, keeping them separate so you can add them just before serving to preserve their brightness.

In a small bowl or container, whisk together the freshly squeezed lemon juice, sherry vinegar, minced garlic, and salt. I find using fresh lemon juice makes a noticeable difference in brightness compared to bottled. Let this sit for a minute to allow the garlic to infuse, then slowly whisk in the olive oil to create an emulsion. Taste and adjust seasoning with a pinch of sugar and black pepper—the sugar should just barely be perceptible, balancing the acidity.

In a large bowl, combine the cooled quinoa from Step 1, the prepared celery and tomatoes from Step 2, the drained chickpeas, and the minced onion. Pour the dressing from Step 3 over the salad and toss everything gently but thoroughly, making sure each component is evenly coated. I like to reserve the fresh herbs and sumac for just before serving—this keeps the herbs vibrant and the sumac's tangy flavor from fading. Taste and adjust seasoning with additional salt and pepper if needed, then top with the remaining 1 tsp sumac and the freshly chopped herbs. Serve immediately or chill until ready to serve.