For the stuffed peppers, cut the peppers lengthwise and remove the skin and seeds. Brush inside and out with olive oil.
Chop the mozzarella, prosciutto and sun-dried tomatoes into small cubes. Peel and finely chop the garlic cloves. Pit the olives and chop coarsely. Pluck the oregano leaves from the stems and chop finely. Mix all ingredients and season with salt and pepper.
Fill the sliced pepperoni with the mixture. Grill on a hot grill – possibly in a grill cup – for about 7 minutes.