It's probably a technique that has been slowly refined and perfected over the centuries. Selectively breeding grapes that preserve well, finding the correct mu

It's probably a technique that has been slowly refined and perfected over the centuries. Selectively breeding grapes that preserve well, finding the correct mud and how much water to mix, working out that saucer shape and how many you can do at once. There are many years of gradual improvements baked into those grapes.