There is plenty of demand for advertising on recipe and food-related sites, you just need to know where to look and not be afraid to incorporate an ad unit on your site with bold letters stating, "Advertise here! Click for details". It makes the site look more authentic for when you do solicit other restaurants and such to make use of your advertising potential. However, I would wait until I had a decent amount of traffic streaming through each day, even 500-1000 uniques is enough to suffice. This way you can give the restaurant numbers and they will be more willing to follow up on the offer. Obviously, the more traffic you have, the easier it will be to find a willing restaurant. The pay rate will also vary on the traffic. If you can manage to get more than 50,000 unique visitors per month, you'll probably be able to sell the ad space for several thousands of dollars per month.
As for Google Adsense, they want only the best quality and high traffic sites for their advertisers. So constantly create the best content you can possibly churn out with facts, recipes, pictures, numbers, connections to social media, you name it. Eventually you will be accepted.