Combine the ingredients for the walnut pesto and refrigerate until ready to use.
Heat a frying pan with a little olive oil and brown the beef on all sides, in batches if necessary. Remove and set aside.
In the same pan, fry the bacon lardons for three minutes. Add the onion and sauté for about 10 minutes until softened and lightly golden.
Add the carrot and celery and cook for a further three minutes.
If needed, add a little more oil, then stir in the cumin, cinnamon and star anise. Cook for 1–2 minutes until fragrant.
Stir in the tomato purée and cook over a low heat for about 5 minutes until it darkens and thickens.
Return the beef to the pot, then add the tinned tomatoes, red wine, beef stock and sugar. Bring to the boil, then reduce to a gentle simmer. Cover and cook for 2–3 hours until the beef is tender and falling apart. Add a little water if the sauce reduces too much during cooking.
Add tinned tomatoes stock and beef back to the pot, combine well, bring to boil then turn to simmer and cover. Let the ragu slowly cook for 2 - 3 hours until beef is super soft and falling apart. If the temperature is too high and your sauce starts to become dry during cooking, add small splashes of water to loosen.
When you are ready to serve, cook the pasta in well-salted boiling water according to the packet instructions. Drain it and stir through the ragù. Divide between plates and top with walnut pesto.