Preheat the oven to 180C/Gas 4/fan oven 160C. Prick the potatoes several times with a fork and put them straight onto a shelf in the hottest part of the oven. Bake for 1-11⁄4 hours, or until they are soft inside.
Meanwhile, put the cottage cheese in a bowl with the tuna, celery, spring onions and some salt and pepper, and mix together thoroughly.
To serve, cut a cross in each baked potato and open it out slightly. Spoon the filling on top, sprinkle a couple of drops of Tabasco sauce over each one and serve with a green salad.