Heat (boil) water in a pot. Add the sausages and let them simmer for about 15 minutes (must not boil). Season vinegar with salt, pepper and sugar. Fold in the oil. Remove the sausage from the water, rinse with cold water and peel off the skin. Cut the sausages into about 6 slices each. Mix with the vinaigrette
Wash the chives, dab dry and cut into small rolls. Drain the gherkins and cut into slices. Place 1 slice of sausage on each cracker. Put 1 blob of sweet mustard on each and spread gherkins on top. Sprinkle with chives. Serve with small wooden skewers of your choice