Place egg yolks and 1/4 cup orange juice in a heatproof bowl or in a double boiler set over simmering water, whisking constantly until warm and just starting to thicken, 1 to 2 minutes. Add butter, 1 slice at a time, whisking each addition until fully incorporated. Continue to whisk until sauce is thickened, 2 to 3 minutes.
Remove from heat and season with salt and black pepper. Thin sauce with remaining 2 tablespoons orange juice to reach desired consistency.
Make the sauce over simmering water instead of over direct heat; too much heat will only cook the egg yolk rather than thicken the sauce. A bowl rather than the top pan of a double boiler makes whisking the sauce easier. Finally, softened butter blends in more readily than the more commonly used melted butter.
To prevent a skin from forming on top of the sauce, cover sauce loosely with a paper towel and set over pan of warm water until ready to serve.
Per Serving: 246 calories;26 g fat;
2.1 g carbohydrates;
2.1 g protein;
198 mg cholesterol;
57 mg sodium.