Wet the potatoes in water. Wrap the wet potatoes in plastic wrap individually and microwave for 3 minutes. Poke with a chopstick to see if it is cooked through. If the potato is not done, microwave a little bit longer.
Microwave the salmon fillet and flake. Mince the onion.
While the potato is hot, peel off the skin and mash. Add the butter, and a splash of condensed milk for flavour.
Cook the minced onion from Step 1 in a pan. You can use oil or butter for this. Once the onion is cooked, mix with the salmon from Step 1, then with the potato mixture from Step 2 and mix well. Season with salt and pepper to your liking.
Form the mixture from Step 4 into golf ball portions. Roll in flour, then in egg, then in panko. Fry the coated balls in oil.
When the croquettes have turned golden brown, remove from the oil. You are now finished. I recommend dressing them with a sauce composed of 1 part mayonnaise and 1 part ketchup.
Story Behind this Recipe
I wanted to make croquettes for the autumn. I think I will try making croquettes with mushrooms or chestnuts next.
You don't need to add ground meat to make these croquettes rich. The butter adds a deeply rich flavour on its own. The idea for using condensed milk as a 'hidden flavor' in croquettes comes from the mother and son food writers Katsuyo and Kentaro Kobayashi. I borrowed the idea from their cookbooks!