Clean the leek and cut into thin rings. Briefly put the tomatoes in hot water, peel and cut into small pieces. Cut the ham into small cubes.
Heat the butter in a saucepan and roast the rice in it. Add the leek and sauté briefly. Pour on the hot broth. Season with salt, pepper and thyme. Cook on low heat for 20 minutes. Possibly add a little more water.
10 minutes before the end of the cooking time, add the chopped tomatoes and diced ham and stir in. Serve sprinkled with chopped parsley. Possibly add grated Parmesan cheese.