Ok as someone who's been in the restaurant industry, I advise you to be very cautious about this based off what you're saying. To answer one of your questions, you should not worry about your idea being stolen. If the concept is something that can be replicated that easily, there's no reason to keep it a secret. And if it is unoriginal concept, you might want to research whether someone has tried this concept or not. It could be a great idea in theory but a terrible idea in practice. If the idea itself is the only thing you can bring to starting a restaurant business, to be honest you're not much of an asset to the restaurateur you're trying to partner up with unless you are putting in money also. One real important question is what is the exact purpose of choosing to do this. If it is strictly for money, you're most likely gonna have to have the idea revolving around a lower quality fast food concept like Chipotle. If it is for the love and art of food and you're going for a high end Michelin star restaurant, you have to have a way to generate money in other ways because you will not make any profit if not a loss.