In a dry pan, gently toast the fennel seeds until fragrant – a minute or two. Remove from the heat and transfer to a pestle and mortar and grind the seeds until they form a powder.
Place all of the sausage meat removed from its casing into a large bowl. Use a whisk to break the meat up into smaller pieces.
Heat 4 tablespoons of extra virgin olive oil in a pan and add the sausage meat along with a pinch of salt and the fennel powder. Sauté the sausage until brown and slightly crispy – we want good colour on the meat.
Remove the sausage from the pan and set aside, reserving as much oil and fat in the pan as possible.
Add the chopped onion and celery to the same pan and cook gently for around 7 minutes, until soft and slightly translucent. Add the garlic cloves and continue cooking for another 2-3 minutes.
Add the sun-dried tomatoes and hot chilli to a blender and pulse to form a paste. Add this to the onion and celery and cook until slightly caramelised and darker in colour – a few minutes – before adding the sausage back to the pan.
Add the white wine to deglaze the pan and let it reduce, before crushing in the fresh tomatoes with your hands and adding the stock and rosemary sprigs.
Cover with a cartouche and simmer gently for 2 hours, stirring occasionally. Add splashes of stock or water as needed so the ragu doesn’t completely dry out. Check the seasoning, adding salt as required/to taste.
Remove the garlic cloves and rosemary before serving.