This is mashed potatoes or These are mashed potatoes

Question

This question arose in the discussion of a language learning app. Its original sentence is in Russian and it says

Это пюре а вот пицца.

The translation from the app is

This is mashed potatoes and here is a pizza.

Sometimes, the app gives a literal translation instead of proper English. In this case, I'd like to know whether it's correct or not. As a learner, I'd say

• This is a mashed potatoe.

but

• These are mashed potatoes.

I'm thinking that if a bunch of potatoes are mashed (although the shape becomes soft and blended) aren't they originally from some potatoes? Or is it possibly that the app considers "mashed potatoes" as an uncountable noun, therefore it goes with "is"?

Answer 1

The app probably takes "mashed potatoes" as a singular noun as a side dish, but yes I feel this translation is off. You are correct to say:

This is a mashed potatoe.

These are mashed potatoes.

This side dish can also be called simply "mashed potato".

Answer 2

There are uncountable nouns, which generally are not seen as discrete substances, but a continuum, e.g., water, air, and mashed potatoes. These are generally treated as if singular, so, "this is water," and "this is mashed potatoes," apply. Then again, "There are mashed potatoes for dinner," is also correct.

There are exceptions, of course (English has few consistent rules):

• "There are both red and gold mashed potatoes." [Plural because they are different types.]
• The Mississippi River and the Missouri River join at the Meeting of the Waters. [Two rivers are two different waters.]
• "J. S. Bach wrote many airs." [Well, a musical air may be countable ;-) ]

Answer 3

The translation is acceptable because we normally treat the noun phrase "mashed potatoes" as singular and uncountable. However it may be better to use the alternative "mashed potato".

This is an example in which the processing of the potatoes transforms them from individual tubers to a "paste". In most cases, such pastes are uncountable: "This is glue", "This is soup". Exceptionally in this case the name of the "paste" retains the apparently plural word "potatoes". However, it is still treated as uncountable and singular:

How much mashed potatoes/A little mashed potatoes etc

This can be avoided by using the equally acceptable name "mashed potato". You will find native speakers shifting from one to the other, sometimes in the same article (BBC Good Food):

Creamy mashed potatoes recipe - This decadent mashed potato uses clever substitutions to reduce fat and calories but maintain a rich creaminess ... The mash goes well with one pot chicken chaseur.