In Hungary the salt and pepper shakers are salt and paprika shakers. At the Caspian Bistro there is S&P but there is also a larger shaker of a dark tart powder, sumac. The sumac used in sumac powder is related to the stuff you're not supposed to touch while hiking and the less toxic bright red berry bushes I found in the undeveloped acres of small town Minnesota. It is a common condiment in Persian and Central Asian cooking.
Sumac is quite tart. It is used wherever you might expect to use lemon, e.g. fish and hummus. It is more broadly common as a component in the herb and spice mix Za'atar (زعتر ). Za'atar is the Arabic word for wild thyme or marjoram, but this term doubles for a mixture (powder or paste) that is used on roast meat and on flat bread, even in yogurt.
Za'atar and sumac have a reputation for improving health and even sharpening the mind. I can't say whether this is mumbo jumbo or not, but sumac does contain tannins, that like wine are supposed to be healthy.
Scouring the internet for recipes, I discovered there is little agreement on what comprises za'atar - aside from thyme. Some recipes call for predominantly sumac, others none at all. I've included my finds and links. I also recommend two sites for information, the blog Desert Candy has a more complete and competent discussion of Za'tar (plus recipe) and for an almost scary dedication to the study of herbs and spices, Gernot Katzer's Spice Pages. I'm including only the ingredients below:
Syrian Za'atar (from Jewish Recipes)
1/4 cup ground sumac, dry
2 teaspoons dry thyme leaves
1 teaspoon cumin seed
1/2 teaspoon paprika
1/4 teaspoon salt
1/2 cup excellent-quality Mediterranean savory or thyme
1/4 cup sumac
1/2 teaspoon sea salt
2 tablespoons sesame seeds
1/4 cup sumac
2 tablespoons thyme
1 tablespoon roasted sesame seeds
2 tablespoons marjoram
2 tablespoons oregano
1 teaspoon coarse salt