Recipe from KLFulmer:

6 beets
Sea salt and fresh ground pepper to taste
3 sprigs fresh thyme
2 Tbs + 1/4 cup Extra Virgin Olive OIl
2 Tbs balsamic vinegar (make sure gluten free to make this a GF
1 t Dijon Mustard (again, make sure GF)

1- Place rack in middle of oven and heat to 400. Scrub beets and
place on parchment paper which is on top of aluminum foil. The
parchment paper is to avoid aluminum contamination. Sprinkle with
salt and pepper and add thyme sprigs. Sprinkle with 2 T of EVOO.
Wrap foil tightly around beets and bake for 1 hr. or until they are
2. When the beets are just slightly warm slip off their skins. Slice
them into 1/4″ slices and place in serving bowl.
3. In small bowl whisk balsamic vinegar and mustard until smooth.
Slow add the remaining 1/4 cup EVOO whisking constantly until it
thickens slightly. Add salt and pepper to taste. Serve beets at room
temperature covered with the vinaigrette.