What is Vermouth sauce?

There is no sauce called "Vermouth sauce". Vermouth is a fortified wine, often used as an ingredient in cocktails or to flavor dishes.

It's possible you're thinking of one of these:

* Vermouth-based sauces: There are many sauces that use vermouth as a flavoring agent, such as:

* Vermouth sauce: A classic French sauce made with white wine, vermouth, butter, and herbs, often served with fish or chicken.

* Mushroom sauce with vermouth: Vermouth is used to enhance the flavor of mushrooms and create a rich, earthy sauce.

* Red wine sauce: Some red wine sauces use a splash of vermouth to add complexity.

* A specific sauce with a similar name: It's possible you heard a mispronounced name or are referring to a dish from a specific region or cuisine.

If you can provide more context, I might be able to give you a more accurate answer!