All of your data is stored in your MacGourmet4Database file, which is usually in Documents, unless you chose another folder the first time you ran MacGourmet. To move your data from one Mac to another, you just need to copy that file from Documents (or whatever folder contains the database, for Mac App Store versions that is usually in Library/Application Support/MacGourmet) on the old Mac to Documents on the new one. You can change the location if you need to in Preferences > Advanced by choosing the folder you want to contain your database file.
You can also always find this file by selecting the "Where is My Database?" menu item from the Help menu within MacGourmet. This will open the folder containing your database.
You don’t need to import/or export your data, and really shouldn’t. Just moving that file should do the transfer for you.