Cook the potatoes in boiling water for about 20 minutes. Cut spring onions into rings. Cut tomatoes in half. Cut gherkins into slices. Mix vinegar and stock, season with salt and pepper and add 1 tablespoon of oil.
Drain the potatoes, quench, peel and slice. Pour vinaigrette over the potatoes. Fold in spring onions, tomatoes and gherkins. Heat the rest of the oil in a frying pan. Fry the sausages for about 4 minutes on each side. Season potato salad and arrange with sausages