"Ratte" ("Rat") is in this case the name of a variety of potato. I have grown a few this year:
This variety is very highly regarded in the chefs' fraternity. It has been described as "a small potato with a unique nutty flavour and smooth, buttery texture." Some people say the taste is reminiscent of Hazelnuts! It is normally grown as a Maincrop, and I have seen some people say that it takes 5 months to mature. I grew mine in the same way as Second Earlies, and they were certainly ready for harvesting this week. In fact I had to throw away a couple, which had gone mushy, a sure sign of over-maturity. Also - and this is the most convincing evidence for maturity - their foliage had died down completely.
I planted two tubers of Ratte, one in each of two 35cm pots. They were planted on 23rd March, so they took just over 3 months to mature. The yield they gave me was 1.47kgs, which is not huge, but then Wikipedia tells me "...it is normally harvested by hand and low yielding. Because of the low yield and hand harvest this variety fetches a high price and it known as a boutique potato", which is comforting to know.
The appearance of the tubers is reminiscent of Pink Fir Apple - quite knobbly - but the tubers of Ratte though have a distinct 'curved pear' shape:
I am reasonably happy with the skin texture of these potatoes, especially since the variety is described as having a "golden speckled skin", so it's not expected to be completely smooth. One or two tubers have a little bit of Scab, but I'm sure that is down to the excessively dry texture of the soil in which I grew them, and next time I know what to do about this (use a medium containing more organic matter).
I am planning to leave these tubers for a few days to firm-up, and for their skins to harden before I use them. That way they will perform more like the maincrop potato they are supposed to be, and not like a freshly-dug "new" potato.
I'll let you know whether I think they taste of Hazelnuts...
P.S. I give you the Whale potato!