Preheat the oven to 375 degrees Fahrenheit (190 degrees Celsius).
With a mandolin, slice the vegetables into discs about ⅛-inch thick.
Place the veggie slices on paper towels in a single layer. Sprinkle with salt. Let sit for 15 minutes, then blot dry.
Lightly spray 2 sheet pans with oil, then place the sliced veggies on the pan in a single layer.
Bake for 20 to 30 minutes, until crisp.
Sprinkle with sea salt. Allow to cool on the pans for about 5 minutes before transferring to a bowl to serve.
Repeat with any remaining veggie slices until you have as many chips as desired.
Bake similar root vegetables together for better consistency. The beets will take longer to cook and dry out than the sweet potatoes, so try to bake them on separate pans. This way, one type of veggie does not burn while the other is still baking.