Preheat the oven to 400°F (200°C).

Wash the beets and wrap each one individually in aluminum foil.

Roast for about 1 hour, or until fork-tender (the exact time depends on the size of the beets). Let them cool completely.

Peel the beets and slice them thinly using a knife or mandoline slicer.

Transfer the beet slices to a container or shallow dish.

Drizzle with olive oil and balsamic vinegar. If using a smaller container, layer half of the beets first, drizzle with half of the olive oil and vinegar, lightly season with salt, then repeat with the remaining beets.

Top with crumbled feta, chopped walnuts, sesame seeds, salt, and black pepper.