Not all walnuts are the same. Depending on the variety, they can have a sweeter or more tangy, even bitter taste.
When you start reading a recipe, you may find that the dish you want to prepare, uses walnuts without the skin covering the kernel.
This skin, which gives walnuts their slightly bitter and astringent taste, can be easily removed in a few minutes.
To peel the kernels, put them to soak in a bowl with some hot or warm water. When the liquid has cooled down, drain the walnuts and peel them. The skin, which has been lifted off by the heat of the water, can be easily removed by rubbing the surface with a clean dishcloth or by using a sharp knife or tweezers.
Another faster method is to put the shelled nuts in a pan of simmering water. When the water starts to boil, blanch the walnuts for 1 minute and then, remove them from the heat. Drain the walnuts, allow them to cool and then, skin them.
Lastly, there is one other method in which the shelled nuts are placed on a tray lined with greaseproof paper and put in the oven pre-heated to 180 degrees for a maximum of 5 minutes. After taking them out of the oven and allowing them to cool down, the skin will come away easily.
In any case, even if the recipe calls for it, you can always use unpeeled walnuts, which will retain their characteristic flavour, after all.