Place in a very deep pot and cover with cold water until floating. Bring to a boil, cut back to a simmer and cook for about 40 minutes or until tender when pierced with a sharp knife. Note - Beets can be a bit messy and stain terribly. By using a very deep pot you won’t have as much splattering.
While the beets are cooking, make the salad dressing by combining the ingredients above starting with the shallot and ending with the freshly ground pepper. Shake well.
Chop the red onion, slice the green apple, place them in a large bowl and toss with the salad dressing and the feta cheese.
When beets are done, cool, peel, cut in half and then slice thinly.