Clean the baby beets and leave about 1-inch of the stems. Wrap them on aluminum foil and roast at 350F for about 1 hour to 1½ hour. Remove from foil and allow to cool. Then peel the skin by gently rubbing it off. You can leave them whole or slice them as you prefer.
In a large bowl whisk salt and vinegar until the salt has dissolved. Add the olive oil and whisk until all blended.
Add the beets and the salad to the bowl and gently toss until all the dressing cover the leaves.
Serve on a plate and sprinkle the crumble feta cheese over it