Preheat oven to 340F. Peel the beets and thinly slice with a mandolin.
Place the beetroot in a large ball and toss with olive. Sprinkle with ground mustard seeds, and salt and pepper per taste.
Grease two baking sheets with olive oil.
Lay beets on baking sheets.
Bake in oven for 30-40 minutes. Let cool to crisp up.
Serve and enjoy!