IngredientsNuts & dried fruitEasy to get wrong
Die Verwechslungthe mix-up
In Mexico nuez on its own almost always means pecan. The walnut is nuez de Castilla, and you have to ask for it by that name.
The two are in the same family and look alike once cracked. In a dough they do not: the pecan is softer, oilier and noticeably sweeter; the walnut is sharper.
Walnüssewalnuts
The kernel of Juglans regia, two folded halves under a thin brownish skin.
The tannins sit in that skin. They make the slightly bitter note that carries Nussecken, walnut bread and nut cake.
Kaufenwhere to buy them
Nuez de Castilla turns up in the mercado and in supermarkets, usually shelled, as halves.
Pick pale kernels. Dark, oily looking ones are old: walnuts are high in fat and go rancid, and then they scratch rather than bite.
Vorsichtwatch out
If you end up using pecans because that is what is there, expect the baking to come out sweeter.
Pull back a little on the sugar in the recipe and toast the nuts first; that puts at least some bitterness back.