Simmering soup is a slow cooking technique for Chinese soups which is simple and easy.
老火汤 (lao huo tang) can be a long tedious affair but all Chinese love them. It literally means old fire soup. In English, it is called simmered soups or slow cooking soup. I even come across long hour soup. You see, there's just no equivalent English words for many Chinese cooking terms.
To simmer is to cook something at barely boiling point (about 100 degree celsius or 212 degree fahrenheit). To start a simmer, bring water to a boil, then adjusts the heat down until gentle bubbling.
Always place the ingredients together with room temperature water into the soup pot and bring everything to a boil. Try not to add the ingredients into boiling water.
Simmering soup is a gentler way to cook soup than boiling because vigorous bubbling toughens meat and damages vegetables. Chinese soups can be simmered from 1 to 4 hours. It has been found that soups that has been simmered for 1 to 2 hours contain the highest level of nutrients.
Chinese soups can be simmered over the stove top using any soup pot. However, a heavy-base soup pot can help reduce the chance of ingredients settling to the bottom and burning. Most importantly, you won't have to keep stirring the soup. If you are using some Chinese herbs in the soup, it is also important to avoid using aluminium or copper pots. Some herbs react chemically with the pots. I would also avoid stainless steel but some people had challenged me about that. It may be easier if you use a slow cooker to simmer soup. My grandma makes a lot of Chinese soups using the slow cooker.
A slow cooker can automatically adjusts the heat to just below boiling point and free your time and hands because you don't have to stay with the soup. The inner pot is made of glazed clay and will not react to any ingredient including Chinese herbs.
You can also use a thermal cooking pot but it is, technically speaking, not simmering soup.
Some recipes do not tell you how much water to use when slow cooking soups. This is common with family recipes because many Chinese mothers cook by experience and gut feel.
The general rule of thumb is 3 times the weight of the main soup ingredient. However, some people like soups with stronger flavour while others prefer lighter clearer soups. So, adjust the amount of water according to your preference.
There are bound to be miscalculation sometimes when measuring the amount of water needed. In the event that the soup seems to be drying up, add hot water to lessen the impact of the change in cooking temperature. Oh, it is better to add hot water halfway instead of using a lot of water in the beginning. It is much harder to reduce liquid without overcooking the ingredients.
An important preparation step for simmering soup is parboiling the ingredients.
To parboil means to partially cook an ingredient. Root vegetables and meat ingredients like pork, beef, and poultry should be parboiled before putting them in the soup.
For meat ingredients, parboiling gets rid of blood and some of the fat. Have you noticed that soups become murky when you add raw meat or bones? There are froth and bits floating on the surface.
It is okay if you don't mind. But most people would strain the soup or scoop the froth and bits up. Save yourself the trouble and time by parboiling your meats first.
Parboiling vegetables is more about leveling cooking time slightly rather than keeping the soup clear. It is not compulsory especially if you are simmering for more than 2 hours.
To parboil, place ingredients in a pot together with room temperature water. Use high heat and bring the water to a boil and boil for about 10 minutes. Drain the ingredients. Rinse if necessary. Let the ingredients cool down before adding them to the simmering pot.
Seasonings such as salt, soy sauce and pepper should not be added too quickly. They should be added when the simmered soup is about ready to be served. Add the seasonings and bring up the soup up to a cheery boil for about 10 minutes right before serving.