1. Roast the red peppers, then peel them. Using a food processor, puree 3 peppers. Cut the remaining pepper into strips.
2. In a large saucepan with a thick bottom, heat the oil over medium heat. Add the garlic and onion and sauté until tender. Add the sliced pepper and continue cooking for 1 minute. Add the rice and stir to coat well.
3. Add 1/2 cup of broth at a time, stirring constantly. Each time the broth is absorbed, add the next portion.
4. After 20-25 minutes, when the risotto is almost ready, stir in the red pepper puree. Continue adding broth, stirring, until the rice grains are creamy but still al dente.
5. Remove from heat. Add the parmesan cheese, season with salt and pepper. Serve immediately.