Put the rice in plenty of boiling salted water, cover and let it swell at low heat for about 20 minutes. Then drain. In the meantime peel and halve the onions.
Hollow out the onion halves slightly. Finely chop the inside of the onion. Wash the herbs, dab dry and chop the leaves, except for some thyme for garnishing, from the stems. Grate cheese. Heat 1 tablespoon of olive oil.
Fry the chopped onion in it. Add rice, tomato juice and herbs. Season with salt, pepper and Sambal Oelek. Fold in cheese. Fill into the onion halves. Place in an ovenproof dish, drizzle with remaining olive oil and bake in a preheated oven (electric range: 200 °C/ gas: level 3) for about 20 minutes.
Wash the peppers and cook in the oven for the last 10 minutes. Serve the onion and pepperoni garnished with remaining thyme and bay leaves.