Boil lentils until tender. In a separate pot do the same with the other vegetables.

Chop the onion and the garlic.

Grate the cooked carrots, the parsley root and the celery root.

Heat the oil in a large skillet. Add the onion with garlic, and then add all the vegetables. Season to taste with salt, vinegar, and pepper.

In a bowl, add one egg at a time to the vegetables and mix.

Pour the mixture into the prepared pan (with baking paper) and bake in 180C/360F for about 40 minutes, or until set.