Answering this question, I made an ass of myself claiming that
- Onions are not used in a real Paella.
- Tomatoes neither.
- Paprika / Pimentón neither as this will overpower the saffron flavor.
I've seen loads of recipes with all of these ingredients in some way or other (and I posted a recipe with all of these ingredients :-( ).
As I understand it, onions are not used because the will 'pass' the rice. I have no idea whether this is true or not, but I've never eaten a paella with onions. Not that I usually eat paella.
The tomatoes and pimentón will impart too much flavor so it will overpower the saffron taste (by far the most expensive spice on earth). Food coloring can be used to make the paella 'saffron' yellow.
The question is, what defines a real paella? One definition of paella is the 'pan' or 'skillet' itself, meaning that whatever rice dish you make in it can be called paella, but I'd rather have a more 'traditional' view as to what ingredients can or cannot/should or shouldn't be used.
- Onions (yes or no)
- Tomato (yes or no)
- Paprika (no :-)
- Saffron (yes)