Finely chop the chili and then fold herbs and chili (to taste) into a bowl of vinegar and oil.
Fry the sausages in a little olive oil.
Grate the Le Gruyère AOP.
Make 4 slits in the buns. Fill them with Le Gruyère AOP and warm them in a hot oven so that the cheese melts. Distribute the sausages into the warm buns and top with chimichurri.