I got this from Raymond Sokolov's "Jewish American Kitchen." I'm posting his introduction as is, because I agree with it 100%. I've tweaked the quantities a bit, and it is delicious. He says "Here is my favorite of all salads. Bland, solid, earthy beets are enlivened with a mayonnaise spiked with horseradish, mustard, sour cream, and scallions." When I make it, I double the sauce because it's so delicious! Total time includes the time to cook and peel the beets.