Using a food processor with a shred attachment, shred the celery root, potatoes and onion. If you don't have one, a box grater with large holes works great.
Working in batches, use a clean kitchen towel and take about a cup of the mixture and tie it up inside the towel and squeeze out as much liquid as possible.
Add the shredded vegetables to a large bowl, along with the eggs, matzo meal and Kosher salt and ground black pepper and stir to combine well.
Heat a wide skillet over medium heat and pour about ½ inch of vegetable oil in the pan and heat the oil so it comes up to 350 degrees Fahrenheit. Use a large regular tablespoon to scoop up the latke mixture and carefully place it in the hot oil, frying 3-4 latkes at a time.
Fry the latkes on the first side for 3-4 minutes and then flip over and fry the other side for another 3 minutes, until golden brown on both sides.
Transfer fried latkes onto a wire rack to drain any excess oil and immediately sprinkle with salt while the latkes are still hot.
For the applesauce, add the chopped apples, honey, cinnamon stick and water to a small-medium pot and bring up to medium heat.
Give everything a stir and place a lid on the pot and continue cooking for 20 minutes until the apples are very soft. If the water evaporates quickly, add ¼ cup more, as needed.
Once the apples are very soft, remove the cinnamon stick and transfer the apples to a food processor and blend until smooth.
Let the applesauce cool and transfer to a resealable container until ready to serve.
Serve the celery root latkes with a dollop of sour cream and spoonful of pink applesauce on top.