Just started photography and I like street photography and city spaces. Then this idea came to my mind: Taking pictures of people that are sitting inside a restaurant eating food. So I am in the street shooting through the windows of the restaurant! Do you think it is a stupid idea? or it can be actually nice? And if you think it can become an interesting subject, then what creative ideas, moments, will you be thinking about if you wanted to do this?
I usually avoid taking pictures of people eating food. It's more or less considered to be not polite.
This is because people usually do not look good while eating. Having mouths open, feeding yourself, some spinach between your teeth, bread crumps in your beard etc.
I accidentally took images of people while they were eating (in the background) and received some barbed remarks.
So in terms of street photography style shooting, people could be quite pissed. I wouldn't like to see some guerilla photographer show up in the window taking pictures of me eating stuff either. This may or may not be one of your concerns.
If you want to combine food and street, I imagine you could start with people at takeaways. Take one kind of portrait image all over again, but with a different person, eating different food at a different location. This could make a nice series.
Or be a little more out there and invite somebody into a restaurant. (you pay the food, they are the subject) I can image interesting pictures of homeless people with what they usually eat every day in a posh restaurant environment but doubt that any restaurant will allow this.
To sum it up: Try to communicate your idea with the subjects.