Parblanch is a cooking technique, but one that doesn’t cook a food item.
Its purpose can be to soak off salt, blood or flavour.
It is not always entirely clear how this differs from just plain “blanch”, because the two terms can be used to describe the same process.
One Parblanching technique starts with cold water. The food item is placed in cold water, brought to a boil uncovered, then lowered to a simmer for a few minutes (usually specified by your recipe) then drained immediately, and put immediately into very cold water to stop any further cooking and / or to firm up the food. The item is then used as directed in the recipe. This process is good for squidgy meat such as some offal like brains.
Another technique can be done starting from boiling water. For instance, unpeeled potatoes, cut in half, placed cut-side down in a pot on a counter or stove not turned on. Boiling water is poured over the potatoes, the pot covered, and allowed to set for 5 to 7 minutes tops. No stove burner is turned on. You can speed up the process by make two shallow slits on the cut side of the potato, on either side of the centre not touching the edges (the slits will allow heat to more easily penetrate the potato.) Then you drain the potatoes, and put them immediately into very cold water.
Watermelon rinds are also “parblanched” before pickling. They’re put in a pot of cold water, brought to the boil, held there for 2 to 3 minutes tops once a boil is reached, then immediately drained and put into very cold water.
Some people will advise to Parblanch anchovies to get rid of the taste, but in that case you might as well save your money on the heating fuel and the anchovies and omit them altogether.