Feel free to substitute some other protein for the shrimps. Cubes of fish fillet or cooked meat will work well too.If eryngii is not available or if you're partial to other mushroom varieties, feel free to substitute as well. Shimeji or shiitake, or even a combination of two or more mushrooms, will do the trick too.What you don't want to make substitutions with are the spices. Without them, the soup will taste flat.