Cut the aubergine into small chunks, approximately 2cm x 2cm. place in a bowl, season with salt, toss to combine and set aside whilst you prepare the other vegetables.
Cut the courgette into chunks the same size as the aubergine. Slice tomatoes in half.
Chop onion finely. Peel and crush the garlic clove.
Using a small frying pan, dry roast fennel seeds over medium heat until fragrant. Transfer to a mortar & pestle and crush down to a powder.
Heat some oil in a frying pan and over medium heat start frying the aubergine. After about 10 minutes when it’s starting to brown a little and get soft, pour in a splash of water (or white wine), turn the heat down and cover with a lid. Allow the aubergine to sauté like this for 5 minutes.
By this point the aubergine should be very soft and surrounded by pan juices. Remove the aubergine from the pan, wipe it down, and add another splash of oil. Start frying the onions until soft. Add garlic, courgette pieces, chopped tomatoes and crushed fennel seeds along with a good pinch of salt. Cook for 5 minutes.
Combine chicken stock, Nduja, red wine vinegar, sugar and passata in a bowl, whisk to combine. Pour the sauce over the vegetables and allow it to come to a boil. Once boiling turn to simmer and cover with a lid. Simmer for 10 minutes.
Fry sausages over medium heat until nicely browned. Add to the vegetable ragu, coating in the sauce and heat through for 5 minutes.
Make the salad: Combine sliced fennel and lettuce in a bowl. Add a splash of olive oil, squeeze of lemon, sprinkle of salt and combine.
To finish: Remove ragu from the heat. Take out sausages. Drizzle the ragu generously with olive oil, add grated parmesan and stir to combine. Taste and season with salt if needed.
Divide vegetable ragu between plates, top with sausages, and garnish with a side of fennel salad. Grate over extra parmesan cheese if you desire.