Wikipedia
Beurre noir is melted butter that is cooked over low heat until the milk solids turn a very dark brown. As soon as this happens, acid is carefully added to the hot butter, usually lemon juice or a type of vinegar. Some recipes also add a sprig of parsley, which is removed from the hot butter before the acid is added.
Beurre noir is typically served with eggs, fish, or certain types of vegetables.
Usage examples of "beurre noir".
Pitt opted for ris de veau ou cervelles au beurre noir, sweetbreads in brown butter sauce served with baked mushroom caps stuffed with crab enhanced by a boiled artichoke with hollandaise sauce.
He and Star Spoon had breakfast, eggs au beurre noir, blue-berry muffins, and figs with cream.
Saturday morning Wolfe buzzed me to come to his room while he was eating breakfast, and when I went, he, having remembered his taboo on talk of business during meals, let me sit and watch him gloomily dispose of four pieces of toast and a dish of eggs au beurre noir.
There was orange juice, eggs an beurre noir, two slices of broiled Georgia ham, hashed brown potatoes, hot blueberry muffins, and a pot of steaming cocoa.