Just returned from Rhodes where we had Karithopeta ( greek walnut cake) & I've found a recipe for it which requires 'farina' where can I buy this or can it be substituted ?

Farina, I'm guessing, means 'flour' but I also believe is a name used for potato starch / potato flour. Why this might be in a cake is beyond me - perhaps a different farina?

Delia made a cake with Potatoes in it, so maybe it is potato flour.

I've seen potato flour in some of the supermarkets in their "free from" aisle.

Farina,from Wiki:
[link]

since it's a Greek recipe,my guess would be - Semolina was originally used and it has been "americanized" for "global" use

(I keep having this problem with many recipes I find,if anyone here knows what "half and half" -please tell me!)

Farina is cream of wheat. You want uncooked (not instant) cream of wheat for this cake. It is what gives the Greek walnut cake its wonderful texture. I ate a piece of this delicious cake most every day I was in Greece, and have successfully made it at home with cream of wheat (farina). Best Wishes!