Pour soda into kefir, stir. When it stops sizzling and foaming, add the rest of the ingredients and knead a very soft dough. Wrap the dough in a film and let lie for 2 hours.
Cut sausages into pieces and fry on all sides.
Divide the dough into pieces, roll flat cakes. Put mustard on each, then sausage. Wrap in the form of pies. Fry in vegetable oil until golden brown.
Put ready cakes in a pan and cover.