½ small lemon, finely grated zest only (optional)
50g/1¾oz baby spinach leaves
sea salt and freshly ground black pepper
20²µ/¾´Ç³ú cornflour
300ml/10fl oz semi-skimmed milk
15²µ/½´Ç³ú Parmesan, finely grated
300g/10½oz mixed fish, including smoked haddock, cod and salmon, thawed if frozen
1 thin slice white or brown bread
100g/3½oz frozen peas, to serve