秘诀 (secret method) is a good counterpart for "the secret sauce"

but am wondering if there are more interesting/idiomatic ways to say this.

There are some similar terms:

• 秘方 (secret formula ) mainly refers to 'unique secret medicinal formula'. It can also be used metaphorically to mean "unique method". Example: The government's 秘方 of lower the housing cost but keep the interest rate high is to build more public houses.

• '絕招' (ultimate technique) is a martial art term. It can also be used as a metaphor for 'unique way'. Example: His 絕招 (unique method) to getting new clients is the 'iPad give-away move'

秘诀 (secret method) is a good counterpart for "the secret sauce"

but am wondering if there are more interesting/idiomatic ways to say this.

There are some similar terms:

• 秘方 (secret formula ) mainly refers to 'unique secret medicinal formula'. It can also be used metaphorically to mean "unique method". Example: The government's 秘方 of lower the housing cost but keep the interest rate high is to build more public houses.

• '絕招' (ultimate technique) is a martial art term. It can also be used as a metaphor for 'unique way'. Example: His 絕招 (unique method) in getting new clients is the 'iPad give-away move'