There used to be a place in Ottawa (downtown in the 'mall' on the bottom floor across the street from the Hudson's Bay - not sure if it is still there) that might have filled the bill that others are describing above - a sort of open food court where diners could choose from a variety of meals and/or assemble their own from bits and pieces of meals cooked at different stations and pay at one cashier area only. Many years ago I went there often and the food was always excellent and the assortment of choices very large - though I don't recall there being much really 'ethnic' representation in the offerings. But, that also brings to mind the many HUGE buffet type 'restaurants' in Vegas - which had (back when I went there a number of years ago now too) many different cuisines one could choose from all done in a single large area, to a pretty high standard. But, again, with either of those places or others like them, one pretty well eats from what the restaurant has on hand and is prepared to cook. There are also 'mongolian' restaurants where one chooses from a large variety of meats, vegetables, sauces, etc. and the 'chef' puts them all in a wok or on a grill and cooks them all to order - perhaps that is closer to a 'choice' for the customer, but, you won't find mac and cheese or grandma's apple pie there either.
But, I don't really think any of the above addresses what I think the restaurant concept that Harrison is trying to research. I heartily agree with all the great 'this is why that concept is a problem' advice everyone here offered. I also think that what is being discussed is, as others have said, what 'personal chefs' do and that is probably not viable in a decent sized centralized restaurant establishment. (eta: I just read Alex's comment about Restaurant Jezebel and that very small place might be able to accommodate diners better but at that price point I doubt that is in the realm of millennials, especially those who are hungry tonight, not tomorrow or next month when they can get a reservation).
Under what circumstances would I like it though, if it were possible? Hate to say it but most probably it would never appeal to me. But, there are people out there who like the 'Blue Apron' idea where ingredients are delivered to one's house and then they have to follow the directions and cook their own 'to order' dinner - but again, the offerings are chosen from a set menu even it varies often, not just at the whim of the customer. Maybe, hypothetically, they would find this idea which takes that whole idea a bit further, intriguing. Could you count on making money from them long term though ... I doubt it. And you would have to operate in a very large city to make it work at all I think - where you would have major competition from the whole roster of ethnic and other specialty restaurants which are also there and well established.
Perhaps what work for me (once or twice, just for fun) would be if I source the ingredients (at least for any that are exotic) and give them and a recipe to someone else (in a restaurant setting where I know the health and safety standards are up to scratch) and they cook it all for me. I pay then only for the cooking and the place to eat it (or maybe I just do take out). But, even that is complicated and fraught with the great possibility of disappointment because not all chefs know all cuisines and believe me, for me not to cook for myself what I have spent time sourcing ingredients for, I would want to be sure that the chef I was delegating that responsibility to was an expert in that particular cuisine. But, then like most here, I LOVE to cook so perhaps I am not the right kind of person to ask about this.
Good luck with your paper.
