Slicing the base of the cauliflower creates a large, smooth surface area, which allows the cauliflower to crisp and brown, while the inside steams to fork-tender. The nice thing about this method is that you don’t need to fire up the oven. Rather, the entire cooking process occurs in a pot on the stovetop.
- Remove the leaves and stem from the cauliflower. Slice off the bottom of the cauliflower just above the root so that it lies flat.
- Melt the butter in a cast iron pot with a lid. Add the herbs. Place the cauliflower, flat side down, in the melted butter. Season with salt. Place the lid on the pot and let cook on medium to low heat for 30 to 35 minutes. After about 20 minutes, flip the cauliflower so the top gets browned. The bottom should be fully caramelized, while the rest of the cauliflower is very tender.
- Remove the cauliflower from the pot. Add the vinegar to deglaze any brown bits stuck to the bottom of the pot and spoon the liquid over the cauliflower. Serve the roasted cauliflower with the hazelnut gremolata.
- To toast the hazelnuts: Preheat the oven to 350° F. Place the hazelnuts on a baking sheet. Toast until lightly colored and skins are blistered. Wrap the nuts in a kitchen towel and let steam 1 minute. Rub the hazelnuts in the towel to remove their skins (don't worry if some of the skins don't come off). Cool completely. Chop.
- Mix all the ingredients together in a bowl. Stir until combined.