Preheat the oven to 390 degrees F. Roast the whole bell peppers in the oven for 20 minutes. Chop and deseed the peppers once they are roasted.
Meanwhile, pierce the tomatoes with a fork and submerge them in boiling water. A minute later, drain away the water, submerge them once more in cold water, and peel.
Chop the eggplants and zucchinis into thin slices. Add to a non-stick frying pan and fry for a couple of minutes on each side, until lightly browned.