Wash and place each beet in tin foil. Roast for 45 - 1 hour -- depending on size. (I pull my beets out when they are individually done, so that the smaller ones don't get overcooked) The beets taste better when they are undercooked.
Let cool on the counter for 15 minutes. With gloves, peel the beets and cut into cubes.
Stir honey with mustard in a medium bowl until combined; slowly whisk in lemon juice and salt. Add beets, gently toss to coat.
If making in advance, bring to room temperature before serving.