Every recipe I have found for making traditional Spanish churros or porras calls for adding the flour to boiling or near-boiling water (or, less commonly, milk).
These are very simple pastries, usually there are only three ingredients: flour added to boiling salted water, then piped into hot oil and fried until golden.
When I tried using room temperature water, the churros ended up heavy and greasy.
Edit: Some answers have maintained that this dough is a Choux pastry. Choux pastry is also made with boiling water or milk, however, it is always made with eggs and butter, and sometimes milk. This seems to be a huge difference, especially when talking about so few ingredients, so I find it dubious that this is even "a variant" of Choux.