Trim the very top and bottom off the leeks. Halve and rinse out any grit. Finely slice it. Warm a pan over a low heat for 1 min. Add ½ tbsp oil and the leeks. Season with a little pepper. Cover. Gently cook for 5 mins to soften the leeks.
While the leeks sweat, peel and grate the garlic and ginger. Halve the chilli. For less heat, flick out the seeds and white bits. Finely chop it. Stir the garlic, ginger and chilli into the leeks. Cook and stir for 1 min till the pan smells aromatic.
Add the chopped tomatoes to the pan. Pour in 600 ml boiling water (or use hot homemade stock). Cover, turn the heat up and bring to the boil.
While the pan comes to the boil, rinse the rice under cold running water. When the soup is boiling, tip in the rice. Add 1 tbsp of the tamari (keep the rest for later). Simmer for 8-10 mins till the rice is tender. Taste the soup and add more tamari if you think it needs it. Serve in warm bowls.