Combine the grated beets, herbs, spices and cheeses in a large bowl. Season with salt and pepper. Add the breadcrumbs and flour and toss well. Add the egg, slightly beaten. Knead the mixture well.

Take a heaping tablespoon of the mixture at a time and shape into 1 1/4-inch / 3-cm balls. Flatten each ball to a patty about 1/2-inch / 1.25 cm thick. Place on a tray, cover, and refrigerate for one hour.

Bring a small pot of water to a rolling boil and blanch the julienned lemon zest for about 1 minute. Drain and repeat one more time. Drain and place back in the pot with a cup and a half of water and half a cup of sugar. Bring to a boil, reduce heat and simmer until the liquid is a thick syrup,about 8 minutes. Remove from heat and remove the lemon zest with a slottted spoon. Transfer to a cutting board and chop.

Mix the yogurt, candied zest, mint, garlic, salt and olive oil together and set aside, refrigerated, until ready to serve.

Remove the beets from the refrigerator. Season a cup and a half of plain flour with salt and pepper. Heat 1/2 inch /11/4 cm of olive oil in a large, nonstick skillet. Dredge the beet patties with flour on all sides and shake off the excess. Place a few at a time in the hot oil and fry over medium heat until lightly browned and lightly crisp on the outside, about 4-7 minutes total, flipping once to cook on both sides. Remove and drain on paper towels. Continue with remaining beet keftedes until done.

Serve hot or at room temperature on a platter together with the lemon tzatziki.