In a large saucepan or pot, heat the oil over medium heat. Once hot, add the onion, garlic, and mushrooms. Sautée for 5-7 minutes, or until onions start to brown a bit.
Next, pour in the water and add the sliced radish, carrot, corn, and tofu. Add the salt, sugar, and soy sauce. Cover and let it simmer for about 1 hour and a half. Taste and adjust seasonings if needed. Stir in the chopped cilantro and remove from heat.
Cook the macaroni in a large pot of water according to the package instructions.
To serve, divide the cooked macaroni between 3 serving bowls and pour the piping hot broth over it. Add some of the radish, mushrooms, carrots, and tofu. Garnish with more fresh cilantro, and serve immediately!
This soup will keep for up to 3 days in the refrigerator, I recommend cooking the noodles just before serving.