1) Cut the tomatoes in half, and remove the seeds. Add the tomatoes and 450ml of stock to a blender and puree. Strain into a bowl and reserve the liquid. Add enough extra stock to make 900ml of liquid.
2) In a large saucepan, heat the oil over medium-high heat. Add the onion and carrots and saute for four minutes until the onion is translucent. Add the garlic and saute for one minute. Stir in the rice and cook until slightly toasted, about three minutes. Add the tomato-stock mixture, stir and bring to boil. Add the salt, bay leaf and the serrano chilli. Reduce the heat, cover and simmer until the rice is tender, about 20 minutes. Remove the pan from heat. Scatter the peas over the top of the rice, cover, and let the rice stand for five minutes. Fluff the rice with a fork, transfer to a serving bowl and serve.
Notes: For a deeper colored rice, stir in two tablespoons of tomato puree when adding the salt, bay leaf and serrano chilli.