Remove the pits from the olives and cut them into round slices. Sprinkle them with a little salt if necessary and mix them with the olive oil.
Cut the buns in half and smear the lower half with a little olive oil. Put a slice of cheese on each, arrange thin slices of sausage on top and sprinkle with the olives.
Bake the buns in a strong oven until the cheese melts.
In the meantime, cut the tomatoes into small pieces.
Take the buns out of the oven, arrange some tomatoes on top and cover with the upper half of the bun.