Preheat oven to 400°F.

Peel the sweet potato and parsnips. Rinse and dry well. Cut the sweet potatoes lengthwise into ¼ to ⅓-inch-thick slices, and then cut each slice lengthwise into ¼ to ⅓-inch-thick fries.

Cut the parsnips in half crosswise. Cut the halves lengthwise into ¼ to ⅓-inch-thick slices, and then cut each slice into ¼ to ⅓-inch-thick fries.

In a large bowl, toss the sweet potato and parsnip fries with 1 tablespoon of olive oil. Arrange in one even layer on a sheet pan. Set aside.

Using gloves, so as not to stain hands, peel the beetroot. Rinse and dry well.

Cut the beetroot crosswise into ¼ to ⅓-inch thick slices, and then cut each slice lengthwise into ¼ to ⅓-inch-thick fries. Use a glass cutting board or large disposable plastic plate, so as not to stain your kitchen tools.

Toss the beet fries with the remaining ½ tablespoon evoo. Arrange in an even layer on a second sheet pan.

Bake uncovered for 40 minutes, rotating the baking sheets in the oven from top to bottom halfway through.

Remove the sweet potato and parsnip baking sheet, and leave the beets in the oven to bake for an additional 6 minutes.

Toss all three colors of fries together with the kosher salt. Serve immediately.