He is very possibly violating your intellectual property--your trademark in the restaurant name and your copyright in the recipes. You should speak with an attorney--probably either a lawyer specializing in intellectual property, or one specializing in business litigation--about your options and potential recourse; you may be able to either stop him from doing this, or else seek monetary compensation.Depending on the exact circumstances, it is possible that there may be other causes of action, such as tortious interference with economic advantage (if the landlord used improper means or pressure to shut you down, so he could reopen the business), so it's well worth consulting with an attorney.