Roughly dice the chorizo and place into a large casserole pan on a medium heat. Cook for a few minutes, or until the chorizo has released its oils, then add the fennel seeds. Peel and finely slice the red onion, add to the pan and cook for a few minutes, or until softened and smelling amazing.
Click away any tatty outer leaves from the red cabbage, trim the base, then cut into wedges and roughly slice. Add to the pan with a swig of red wine vinegar, and a pinch of sea salt and black pepper. Cook with the lid ajar on a low heat for 10 minutes, stirring frequently. Add the tinned pears, with some of the juice, and continue cooking for a further 10 minutes, or until the cabbage is tender.