Step 1

In a thick-bottom skillet, melt butter over medium heat. Once the butter is fully melted, reduce heat to medium-low, and continue sizzling the butter, swirling the pan occasionally, until the thick, dense foam cooks off and the bubbles get bigger and more clear. You'll see that the milk solids are separated from the liquid. Reduce heat to low and cook, whisking constantly, until you can see that the solids have turned a rich brown, and the liquid fat is darkening as well, closer to the color of a stout than that of an IPA. The whole process should take 5 to 10 minutes, depending on how hot your stove is. The lower your heat, the darker you'll be able to toast the butter without burning it.

Step 2

The moment you see the right color, remove the pan from heat and add your chopped sage and shallot. Sizzle and swirl in the hot pan for about a minute, then transfer to a heatproof bowl.  Add salt, pepper, red wine vinegar, balsamic and lemon juice, and whisk together until vinaigrette looks glossy and smooth. Taste and add salt to your preferences.

Step 3

Use immediately or refrigerate for up to three days. To reheat, microwave in 10 second increments until the butter is completely melted, then transfer to a bowl and whisk until the fat and vinegar are reincorporated.