Gather all ingredients and measure the wine, vinegar, shallots, and chilled butter before you begin.

Combine 1/2 cup dry white wine and 1/4 cup white wine vinegar in a small saucepan over medium heat and bring to a gentle boil.

Add 2 finely chopped shallots and simmer for 5 minutes, stirring occasionally, until the shallots are softened.

Reduce heat to medium-low and continue simmering until the liquid reduces to about 2 tablespoons, about 5 minutes.

Lower the heat to low to prevent the butter from separating.

Whisk in 1 cup cubed chilled unsalted butter a few cubes at a time, whisking constantly to emulsify the sauce.

Season with salt and pepper to taste, stirring to incorporate.

If a smoother texture is desired, strain the sauce through a fine mesh strainer before serving.