If necessary, adjust the amount of water or flour until you get the standard density of pancake batter. Allow it to sit for 10-15 minutes.
During this time, chop the onion/leeks and tear up the salmon fillets. Lightly grease a frying pan and pour the mixture in with a ladle.
Spread the pancake batter in the pan and once done on one side, flip it over and do the other. Allow to brown briefly and distribute the onions on top, which you've pre-fried separately, and the pieces of fish.
Fold the pancake around the fish and put it on a plate. In the same way, prepare the other pancakes.
The amount depends on the size of the pan you are using.