Don’t forget to cover the bowl containing the chickpeas and shallots when microwaving. Covering traps steam that helps wilt the shallots and soften the chickpeas. And remember to occasionally stir the chickpea-shallot mixture as it cools. This helps ensure the chickpeas evenly absorb the seasonings pooled at the bottom of the bowl while also hastening the cooling.
In a medium bowl, whisk together yogurt, tahini, lemon zest and juice, 1½ tsp oil, ½ tsp salt, and ¼ tsp pepper; set aside.
In a large microwave-safe bowl, stir together chickpeas, shallot, vinegar and za’atar. Cover and microwave until shallot is wilted, 1½ to 2 minutes. Uncover and cool to room temperature, stirring occasionally.
When chickpeas have cooled, stir in remaining 2 Tbsp oil, zucchini, mint, dill and cilantro. Taste and season with salt and pepper.
Scoop yogurt mixture into a mound in the center of a large platter. Transfer the chickpea-zucchini mixture to the platter, spooning it around the yogurt mixture. Drizzle with additional oil and sprinkle sumac (if using).