True beef or not true beef? That is the question two volunteers sampling a burger in front of an invited audience in a London theater attempted to answer earlier today. Expensive food is often served as performance art and this version of the global fast-food staple may be the exemplar of that form: it had taken three months and eaten up €250,000 ($331,400) to develop in a laboratory. “It’s close to meat,” mused the first taster, Hanni Rützler, a nutritional scientist, swallowing the too-solid flesh with some difficulty. “This is kind of an unnatural experience,” confessed the second taster, Josh Schonwald, a writer, as he chewed on history. He meant the lack of ketchup.