Do not conflate with Peanut or tree nut allergy. Each restaurant page explains the evidence and what remains uncertain.
If you're checking the standard Chick-fil-A Chicken Sandwich for sesame, don't rely on whether you can see seeds. The bun ingredients list sesame flour, and the sandwich identifies sesame. A bun-free order removes that listed bun, but you'll still want to ask how staff assemble it.
If you're checking a McDonald's order for sesame, don't rely on whether you can see seeds on the bun. The Triple Cheeseburger's regular bun says it may contain sesame, and McDonald's warns that normal operations may use shared preparation areas, equipment, and utensils.
If you're ordering a Starbucks drink with a sesame allergy, review the complete build even when sesame isn't obvious from its name. Check the milk, syrup, sauce, cold foam, topping, powder, and seasonal garnish for the exact recipe. Starbucks also lists sesame in foods such as the Eggs & Cheddar Protein Box, but the food menu shouldn't be your shortcut for judging a drink.