This sauce is a riff on English bread sauce, which is a savory sauce that is made with milk and onion thickened with bread or breadcrumbs and butter. Celeriac is the thickener here, making this not only a sauce but a side dish as well. This can be served either warm or cold to accompany main course dishes, such as chicken or pork, or as part of a vegetarian meal. The spices and herbs listed are those used in the traditional bread sauce, though any number and combinations of spices and herbs can be used, depending on the nature of the meal. Again, other roots, such as kohlrabi, turnips, even beets, can sub for or combine with the celeriac.
1 small onion, peeled
2 1/2 c milk or a combination of milk and cream; or milk substitute
2 bay leaves, coarsely crumbled
1/4 t mace
1 garlic clove, peeled and smashed, left whole
2 T butter
3 c or so peeled, diced celeriac
salt and (white) pepper, to taste
1. Stud peeled onion with the cloves. Put into a sauce pan with the milk, crumbled bay leaves, mace, and garlic. Bring just to the boil, then remove from heat and allow to infuse for about 10 minutes.
2. In a large skillet or saucepan, melt the butter. Add the celeriac and stir to coat with the butter. Strain the milk mixture over the celeriac (carefully!). Season with salt and pepper and bring to a simmer. Simmer until the celeriac is very tender. The time will depend on the size of the pieces. if you like, you can remove the cloves from the onion, chop the onion and add to the celeriac. If the milk separates or curdles, do not despair.
3. Remove the skillet or saucepan from the heat. Transfer to a food processor or blender and purée to desired consistency. Transfer to a serving dish and serve warm, at room temperature or cold.