You can tell water or sauce is boiling when it is bubbling vigorously – you can achieve this by using a high heat • Simmering is the stage you get before or after boiling, when water is on its way to boiling or is cooling down from boiling and bubbling gently either on a low or medium heat • You can control how gentle the simmer is by changing the heat underneath the pan JAMIESHOMECOOKINGSKILLS.COM © Jamie Oliver. Photography © David Loftus / Matt Russell.