In the recipe, before we already cooked sausages, so we will just use them.
Cut the peeled onions into thin half-rings. Cucumber - in circles, tomato - in arbitrary pieces.
For the sauce, mix two kinds of mustard and apple cider vinegar. Add pepper and salt.
Generously grease each bun with the resulting aromatic sauce. Add lettuce leaf inside, put on top of fried sausage on top of it. Put the remaining vegetables on top and add more sauce.