Heat oil in a heavy pot over a moderate heat. Add onion, and cook until is starts to turn translucent. Add the garlic and carrot, and cook for about 2 minutes. Stir in the rice. Add chicken stock, tomato paste, salt, and pepper. Bring to the boil, stir once, and reduce the heat. Cover and simmer until all the water is absorbed. Take off the fire and allow the rice to stand covered for about 5 minutes. Serve warm.