Cook
the potatoes in a large pot of salted, boiling water
for 15-20
minutes, or until tender.
Drain and cut into small cubes.
Preheat the oven to 450°F/220°C/gas 7. Oil a
roasting pan. Finely chop 1 tomato and mix with
the potatoes, celery, and zucchini in a large bowl.
Mix in 6 tablespoons of oil, the garlic, basil, and
2 tablespoons of Parmesan. Season with salt.
Spoon the filling into the bell pepper halves and
arrange them in the roasting pan.
Thinly slice the
remaining tomato. Top each of the peppers with a
slice of tomato and an olive. Sprinkle with oregano
and the remaining Parmesan. Drizzle with the
remaining oil.
Bake for
30-35
minutes, or until the bell peppers are well cooked.
Serve hot.