I hate to tell you that most people don't care about your newsletter. People are not part of your network of contacts for you to supply them with content. Most people join restaurant contact lists because they want offers and promotions, not a lengthy story about how special your grandma's recipe is.
People who initially visit your website are leads. Leads are interested in dining with you but not ready to make a reservation or stop by for a visit.
Capturing information from these leads is crucial in your marketing plan.
The best way to capture these leads is to exchange their contact information with something they want: an offer or a promotion.