Ground sumac adds a lemony flavor to these quick-pickled onions from Maydān restaurant. Versatile and bright, use them to top Maydān's Slow-Grilled Cauliflower with Tahina and Zhough.
Bring vinegar to a simmer in a small skillet over low. Remove from heat. Toss together onion slices, sumac, and hot vinegar in a medium bowl until well combined. Refrigerate in an airtight container up to 5 days.
Find sumac at Middle Eastern grocery stores or online at burlapandbarrel.com.