Brush the peppers with a little oil and bake them in the oven until their skins are softened and ready to peel off. Let them cool and peel. Cut them in strips.
Prepare the sauce: place the peeled and finely chopped tomatoes in a bowl. Add the olives, garlic, 4 tablespoons of olive oil, oregano, salt and pepper and refrigerate for about 1 hour. Boil the spaghetti, drain it and mix it with the chopped-up feta cheese. Add the baked peppers and the sauce. Mix and serve immediately with a garnish of basil and freshly ground pepper.