Place the beets in a medium-size saucepan. Add enough water to cover the beets by two inches. Cover the saucepan and bring it to a boil. Reduce the heat to simmer on medium-low for 1 hour, or until fork-tender. Remove the beets and place them on a plate to cool. Once the beets are completely cool, peel them. Slice or dice the beets.

To cut the fennel: Slice the fennel in half and remove the core at the bottom, similar to the endive. Lay the cut side of one half of the fennel bulb on a cutting board. Thinly slice across, then repeat with the other half.

To cut the radicchio: Cut the radicchio in half. Remove the core at the bottom. Lay the cut side down on the cutting board and slice it into thin pieces.

Place the arugula in a large salad bowl. Add the apple, endive, fennel and radicchio. Reserve the dressing until ready to serve the salad.

In a small bowl, combine all of the salad dressing ingredients and whisk together. Adjust to taste. Feel free to double this amount of salad dressing if you like a lot of dressing on your salad or prefer to have extra. When ready to serve the salad, add the beets to it. Pour the dressing over the salad. Toss to combine.

Store the salad covered (without dressing), in the refrigerator for up to 5 days.