Salmon spaghetti soup with broccoli pesto

Name: Salmon spaghetti soup with broccoli pesto
Ingredients: 1 tbsp olive or rapeseed oil; 320g carrots, finely diced; 165g celery, finely diced; 2 onions, finely chopped (320g); 2 large garlic cloves, finely grated; 1⁄2 tsp dried oregano; 2 tsp vegetable bouillon powder; 400g can chopped tomatoes; 2 tbsp tomato purée; 100g wholemeal spaghetti; 400g can cannellini beans; 460g wild salmon fillets, skinned and cut into chunks; 185g broccoli, cut into florets, stalks chopped; 15g fresh basil, plus a few leaves; 1 tbsp lemon juice, plus finely grated zest of 1⁄2 (optional)