Heat the butter in a heavy-bottomed pot. Stir in the chopped onion and the rice until well crispy. Add the vodka or brandy and let evaporate.
In the meantime prepare a light stock using vegetable stock cubes and/or carrots, tomatoes, celery and one potato. Chop the salmon in thin stripes.
To make the risotto: add the hot stock, ladle by ladle, having the patience to wait for the liquid to be absorbed while you keep stirring vigorously. When it is nearly done – taste it until you get the right texture! – adjust the seasoning. Switch off the heat and throw in the salmon. Leave the risotto to rest for a few minutes off the heat before serving.