Wash the potatoes and cook in the peel for 25 minutes. Drain, cool, peel and cut into cubes.
Potatoes and capers are put in a salad bowl (capers are almost impossible to find in the store, if you, like me, have problems with capers, then green olives are quite suitable).
Cut tomatoes into halves.
Olives, if they are large, cut in half, leave the small ones whole.
Cook the sausages, cool and cut into small cubes.
Cut the onion into rings.
Add tomatoes, olives, sausages and onions to the salad bowl.
To prepare the filling, lightly whisk the vinegar with oil, salt, pepper. Pour this sauce over the salad. Let it brew for 30 minutes.