soupcon

If you ask the waiter for a soupcon of hot sauce on your omelet, he will give you a dash of Tabasco, provided he knows what soupcon means.

It's hard for English speakers not to think of soup when they see this word, especially since it can mean a trace of something (such as a flavor), but the ancestor of soupçon is the same one that gives us suspicion and suspect, the Latin suspectionem: the common theme is that of an idea formed from scant evidence.