Neighbour isn't allow salty soups, too much sodium. But the non
Sodium soups have no taste or flavour. What other spices could he use that
Doesn't have sodium in his soup.

'Mrs Dash', an alternative to salt. Works for me. Available in the spice section of the grocery store.

Great news for the soup

Carrot and onion have sweet taste. After shimmer in oil and put them to boiling water. While serving, put some spices on top of the hot soup to make it smell good.

Radish and papaya also add sweet flavour to the soup. Other idea: Lemongrass, ginger and shrimp Thai-style soup.

Very good suggestions