I think this is a really great idea for being the first on steemit. I would prefer a A5 format. cookbooks are sometimes brought around in bags, so I would prefer it to be an 'easy size'. B5 is also fine for me actually.

It is definitely your choice if you want to have a focus on the food. Maybe you can come up with various editions next time. For example, christmas edition, cookie edition etc etc. You get the point.