Hollandaise sauce (/hɒlənˈdeɪz/ or /ˈhɒləndeɪz/ ; [ʔɔ.lɑ̃.dɛz]) is an emulsion of egg yolk and liquid butter, usually seasoned with lemon juice, salt, and a little white pepper or cayenne pepper. In appearance, it is light yellow and opaque, smooth and creamy.The flavor is rich and buttery, with a mild tang added by an acidic component such as lemon juice, yet not so strong as to overpower mildly flavored foods. Hollandaise is one of the five sauces in the French haute cuisine mother sauce repertoire.he flavor is rich and buttery, with a mild tang added by an acidic component such as lemon juice, yet not so strong as to overpower mildly flavored foods. Hollandaise is one of the five sauces in the French haute cuisine mother sauce repertoire.