The first mouthful of “cultivated" meat is both remarkable and dull. In a homely kitchen at the California headquarters of Eat Just, a startup, a playing-card-sized slice of meat has been glazed and grilled. It is served with a sweet-potato puree, maitake mushrooms and some pickled peppers. The meal is remarkable because the meat was grown in a lab , rather than on an animal. It is mundane because the texture, taste, look and smell of the meat is almost identical to that of chicken. And that, of course, is the point. The cultivated-meat business hopes that this experience will...