Simmer it

Simmering is when liquid remains close to, but just under boiling point. Back to the pan of water on the hob. We turn the heat down and the surface of the water is still moving, but not as furiously. There will be evaporation, but not at the same rate and we can prevent this by simply putting a lid on our pan. We simmer the liquid to cook the vegetables in Leek and potato soup.