First, you need to find a place where soup restaurants have some special privileges compared to normal businesses. Then, just start a soup restaurant there and serve cereal and milk instead.

If you can’t find such a place, then maybe you can ask your local politicians to pass a bill like that. Would be nice if soup restaurants had to pay only half the amount of taxes compared to everyone else. Would be good for the owners, and fun for everyone else to see where the resulting legal battles go. Suddenly, you would find lots of companies selling just about anything and everything as soup and claiming they don’t have to pay the usual taxes.