Squeeze as much liquid out of the grate root vegetables as possible.
Place carrot, potatoes, parsnip, garlic, and fontina into a mixing bowl and toss together.
Add egg white, flour, baking powder, salt, and pepper. Mix together until well combined. Allow mixture to sit for 5 to 10 minutes.
Pour oil into a heavy bottom skillet and place over medium-high heat.
Place a few, 2 tablespoon mounds into the skillet and gently press to flatten.
Pan fry for 4 to 6 minutes. Flip and fry for an additional 2 to 3 minutes.
Drain on paper towel and lightly season with salt and pepper.
Repeat until all fritters have been made. Serve immediately with sour cream.