In a large mixing bowl add the potato, salmon, spring onion, lemon juice, parsley, chives, peas, mustard and 1 egg (beaten). Mix until combined but try not to overmix, leaving some texture.
Take a heaped tablespoon of the mixture and form into croquettes. I made 19. Place on a baking tray and chill for at least 15 mins. *SEE NOTE 4
If baking, preheat the oven to 180C / 360F.
Beat the remaining egg and place in a shallow dish. Place the breadcrumbs in a separate shallow dish.
Dip the croquette in the egg and then coat in the breadcrumbs and return to the baking tray. Repeat for all croquettes.
Spray or lightly drizzle with oil. Place in the oven for 20 min, until cooked through and golden.
Alternatively, heat a non-stick frying pan over a medium / high heat. Add 2 tbsp of oil and gently place the croquettes in the frying pan. Fry for around 4-5 min on each side.