Clean and trim the brussels sprouts and boil them for 7-10 minutes. Or till they are nicely cooked all the way through.
Fry the pancetta cubes in a drop of oil until they are lighty browned. Drain off the fat and keep the cubes on a kitchen paper so the grease can get absorbed.
Heat the rest of the vegetable oil in a small pot or pan and fry the sage leaves in a few seconds till they are translucent and crispy. Move them to a kitchen paper and season lightly with salt.
Melt the butter in a clean pot and add the Brussels sprouts and pancetta. Heat thoroughly and add the sage at last.