Cook pasta following packet directions. Drain and keep warm.
Meanwhile, heat oil in a saucepan and sauté onion and garlic for 2-3 minutes, without colouring until onion is translucent. Add tomato paste, reduce heat and cook for 2-3 minutes stirring continuously.
Add stock, diced tomatoes and season to taste. Reduce heat and simmer for 10 minutes until sauce is thickened and tomatoes have broken down. Stir in sugar.
Heat oil in a small frypan and cook zucchini on both sides until golden. Stir into tomato sauce.
Toss sauce through hot pasta. Gently fold through salmon leaving large visible salmon chunks. Serve immediately sprinkled lemon zest and extra pepper.