Question about Indian food

Question

There's a question about how we went to an Indian restaurant and ate everything because it was very rich. The thing they're eating is "food," but the answer wanted you to use "todo." They had it agree with the adjective of rich, but there's nothing that indicates a masculine noun.

Answer

Hola Eylfable
In the lesson, after we explain the different forms of todo (todo, -a, -os, -as), we have this note:
"Todo (masculine singular) can also replace a whole idea, or could refer to "everything" as in a group of things, but as a unit. For example:

Yo quiero verlo todo. 
I want to see everything.
Todo me parece interesante. 
Everything seems interesting to me.

In this case, with the example of the Indian food, that "eating everything" reflects that idea, as in "everything that we were served, that we were offered, that was there to try..." 
I hope this clarified it.
Also, please note that when we say "todo estaba riquísimo", that meaning of "rico" is "delicious", not "rich". 
Saludos
Inma