A question about a recipe: Mussels in a Yellow Tomato Lemongrass Broth

The yellow-orange tomatoes (such as standard orange, or German-Striped) are milder, a bit sweeter, and lower in acidity which translates into a more delicate soup. They're still in season where I live. Best to use local tomatoes when they're in season. I haven't tried with other types of tomatoes, so not sure how it would change the flavor of the soup.

No difference, well, not much, other than color. There is a *slight* taste difference between the colors of tomatoes, but in a highly spiced broth (lemongrass is assertive, for sure), you likely wouldn't notice a significant change in taste. Obviously, the color will be radically different, depending upon which variety you use. But as @pierino said, tomatoes are a Summer fruit (act now, they're going fast, my plants are already spent). Out-of-season/hothouse/ipmorts will never give you the flavor of Summer tomatoes, no matter the color.

Well, tomatoes are a summer fruit period no matter which color strain you are talking about. Of course you can buy hothouse tomatoes and imports all year.