Is there a healthier substitute for the sausage which may provide a similar depth of flavour?

I used a vegan alternative of 'Smoked Turkey Kielbasa'. I'm sure the flavor was not as pronounced as the real thing

And it's turkey kielbasa so it isn't quite as fattening as you think. I would just reduce the amount (and perhaps dice it up to spread it out) if you are really concerned about fat. It's a fairly lean soup to begin with.

If you substitute Shiitake mushrooms for the sausage, you will definitely (not defiantly) NOT be making Caldo Verde. Curious why you think the sausage would be unhealthy? As has already been mentioned here, a moderate amount, occasionally could not be considered unhealthy. And the Chourico is an essential ingredient in this soup.

Kielbasa is much leaner than regular sausage. Anyway there's nothing inherently unhealthy about kielbasa or sausage unless you're eating huge quantities, often. It's always great if you can use organic. Just drain it properly (drain on paper towels or a clean kitchen towel, and pat off the fat). The small quantity that goes into this soup is really nothing to worry about unless you're concerned about making a meat-free dish.

thanks, i have dried shitake mushrooms in the pantry at the moment, ill defiantly give that a go

Shitake mushrooms or smoked chicken.