Background

Compared to other foods, soup seems to be useless, and with good reason. Soup just has several problems that places them below other foods

• Soup is unstackable. What is better: 1 soup or 64 bread?

• Soup themselves are not the best food source. Looking at the wiki, all the soups are below carrots, potatoes, and some meats in terms of saturation. Rabbit stew especially becomes less "viable" since the whole is less than the sum of its parts.

Suggested Changes

My suggestion is changing soup to be similar to firework stars. You can add different ingredients to a bowl to get different soups, and the final products be as strong as all the components together.

Example done in paint. In this case, the soup would fill about 5.5 hunger sticks (steak gives 4 and carrots 1.5. Mushroom has no effect for now).

Ingredients can include meats, vegetables, mushrooms, and maybe other stuff (cacti or pumpkins, anyone?)

This changes makes more sense with 1.9's changes to health regen, a full saturation means faster healing. Soup now has a specific niche; it can fill the hunger bar fully and heal the player quickly. In return, it takes up one whole slot and can't sustain a player for a long trip.