Bernaise Sauce

1 tablespoon plus 1 cup (2 sticks) unsalted butter, cut into 1/2″ cubes
3 tablespoons minced shallots
Kosher salt and freshly ground black pepper
2 tablespoons Tarragon infused Plum Vinegar
2 large egg yolks
1 tablespoon (or more) fresh lemon juice
1 tablespoon finely chopped fresh tarragon

Melt 1 tablespoon butter in a small saucepan over medium heat. Add shallots and a pinch of salt and pepper; stir to coat. Stir in vinegar, reduce heat to medium-low, and cook until vinegar is evaporated, 3-4 minutes. Reduce heat to low and continue cooking shallots, stirring frequently, until tender and translucent, about 5 minutes longer. Transfer shallot reduction to a small bowl and let cool completely.

Meanwhile, fill a blender with hot water to warm it; set aside. Melt remaining 1 cup butter in a small saucepan over medium heat until butter is foamy. Transfer butter to a measuring cup.

Drain blender and dry well. Combine egg yolks, lemon juice, and 1 tablespoon water in warm, dry blender. Purée mixture until smooth. Remove lid insert. With blender running, slowly pour in hot butter in a thin stream of droplets, discarding milk solids at bottom of measuring cup. Continue blending until a smooth, creamy sauce forms, 2-3 minutes. Pour sauce into a medium bowl. Stir in shallot reduction and tarragon and season to taste with salt, pepper, and more lemon juice, if desired. DO AHEAD: Can be made 1 hour ahead. Cover and let stand at room temperature.