Add the egg yolks, lemon juice and spices to a blender and blend on medium.

If your blender has a small opening at the top, keep it running while you slowly pour the melted fat into the blender. If there is no opening, add a small amount of the melted fat and blend, continuing until done.

Once the sauce has emulsified, pour it into a container and use immediately. If the sauce thickens, add hot water to thin it out to your desired consistency.