Place beets in a pot, cover with an inch of water, and simmer. While beets are cooking, slice fennel very thin. Chiffonade (cut into small ribbons) the mint. Zest oranges/lemons and juice them into a bowl. When beets are cooked, drain and rinse under cold water. Peel skin off beets and chop into 1/4-inch thick quarter-rounds. Put all ingredients into a large bowl and mix well. Optional: Throw in some toasted walnuts, goat cheese or sheep feta and serve on farm-fresh lettuce.