I happen to like salad, but as a side to a main meal (the salmon sounds great, by the way). The problem is, it's not particularly filling on its own, meaning I'm looking for something else to eat not longer after, if I just had a salad as a meal. Maybe this is how it is for your husband.
I realise how frustrating it is, but surely your husband should be allowed to choose what he wants to eat, even if it differs from your choice. My wife and I share the same meals three or four times a week. All other times we eat what we feel like, and wouldn't dream of trying to force the other to eat a meal they don't want. Your DH may be just as fed up with you expecting him to have what you're having, as you are with him not wanting it.
As it happens, there's usually a solution to a problem. Here is something I have done in the past. How about suggesting a salad including cold rice? Add the salmon too. This would provide something more filling and could be a good compromise. You could add hard boiled eggs to a salad. Someone has suggested having potato salad as well - great idea.
There are ways to compromise but at the end of the day, people should be able to eat the food of their choice.