Based on the provided search results, there is no specific product listed as a branded “Premium Sauce Bercy 250 g.” However, Sauce Bercy is a classic French, high-quality (premium) sauce used for fish and seafood. 
Here is a breakdown of what a Premium Sauce Bercy generally consists of, based on classical French cuisine:
Definition: Sauce Bercy is a classic French reduction sauce named after a district in eastern Paris, famous for its wine heritage.
Key Ingredients: It is made from a base of dry white wine, shallots, fish stock, and butter, often finished with lemon juice and parsley.
Usage: It is explicitly designed to be served alongside fish and delicate seafood.
Characteristics: It is a, light, umami-rich sauce intended to enhance, rather than overpower, fish.
Context: It is considered a classic “small sauce” derived from the traditional French mother sauces (specifically from velouté).