Add leftover rice and water to a medium size pot. Add in dried shiitake mushrooms and chicken bouillon. Mix.
Using high heat, bring pot to a boil then turn down heat to low/medium. Stir occasionally and continue to simmer. If you notice that the water has gone down, you can add another cup of water and turn down the heat.
When mushrooms are tender (about 30 minutes), remove from pot and slice thinly. You can remove and discard the stem if they are still hard. Add sliced mushrooms back to pot and stir.
Continue to simmer stirring occasionally until rice has become porridge (about 20 more minutes). Add more water as necessary. Total cook time should be 45 minutes to 1 hour.
When porridge is ready, add to a bowl and serve as is or with chili oil, chopped green onions, fried shallots and garlic. If you prefer a saltier congee you can drizzle a little bit of soy sauce or sesame oil to each serving bowl.
