In a small frying pan, heat 60 g of oil. As soon as the foam disappears, add the sage leaves and fry them for two minutes, mix once. Transfer the sage onto a paper towel, sprinkle a pinch of salt and leave.
Fry the sliced nuts on the same frying pan on low heat. Cook them for three minutes, then turn off the fire and put them aside.
In a large frying pan or stew pan, heat the remaining butter. Fry onion diced onion (about 10 minutes on medium heat). Add finely chopped Brussels sprouts, mix, pour in water or broth and cook under the lid. After 10 minutes, remove the lid, increase the heat and evaporate the water. At the end, add the vinegar or sherry.
Transfer the dish into a bowl and mix it with sage and nuts. Serve hot.
