Brown Butter

Black Butter Sauce (beurre noir)
One step further and more dramatic: Cook the brown butter until black flecks start to form, another 2 to 3 minutes. Immediately drizzle the butter over whatever food you are serving, then turn the heat to medium and rinse the pan with 2 tablespoons sherry vinegar or white wine vinegar, swirling it and letting about half the liquid evaporate. Add 1 tablespoon drained capers if you like and 1/4 cup chopped fresh parsley. Sprinkle with salt and pepper and drizzle over the food. Toss if necessary and serve.

5 simple additions to brown butter
Stir in any of these during the last minute of cooking, when the butter is just about ready (this point is easy to recognize once you’ve made it a couple of times). If you want to use them in combination, increase the quantity of butter by 2 tablespoons for each additional ingredient.

1. Finely ground nuts (1/4–1/2 cup): The usual ones, like hazelnuts, cashews, pistachios, walnuts, or almonds. But also macadamia nuts, sunflower or pumpkin seeds, or whole pine nuts.
2. Chopped fresh herbs: 1 tablespoon or so of oregano, rosemary, sage, thyme, or tarragon; up to ¼ cup milder herbs like parsley, cilantro, mint, dill, or basil; or 1 fresh bay leaf
3. Mustard: Up to 1 tablespoon of either Dijon or whole grain, to taste, whisked in
4. Vinegar: About 1 tablespoon of sherry vinegar or balsamic vinegar, which will make a “broken” sauce rather than emulsifying into the butter
5. Anchovies: 2 or more mashed anchovies