Seafood and corn chowder

Name: Seafood and corn chowder
Prep time: 20 min
Cook time: 40 min
Total time: 1 h
Cuisine: American, Southern
Ingredients: 1 lemon, zest only, no white pith; 50 g Parmesan cheese, cut into pieces; 5 sprigs fresh flat-leaf parsley, leaves only; 2 - 3 tbsp pine nuts; 2 - 3 leeks, white and light green parts only (200 g), cut into pieces; 200 g fennel, trimmed and cut into pieces; 40 g salted butter; 2 tbsp cornflour; 2 tbsp dry sherry (see Tips) (optional); 650 g water; 1 tbsp Chicken stock paste (see Tips); 40 g lemon juice; 1 tbsp fish sauce; 200 g potatoes, peeled and cut into cubes (1 cm); 1 sprig fresh thyme, leaves only; 1 dried bay leaf; 100 g bacon, cut into pieces (1-2 cm) (optional); 500 g fresh seafood marinara mix; 400 g canned sweet corn kernels, drained (approx. 300 g after draining); ground black pepper, to season