For your first example, I'd add an item to my Someday/Maybe list "Try the tempura at Wasabi." For your second I might have an entry called "Potential Gifts to Give" and list things I think of that I might want to give to someone someday, along with pertinent info like where to buy/$/who it might be appropriate for, etc. I actually do have a list called "Things I Want".

The trick here is that you are reviewing your Someday/Maybe list appropriately. I review mine once a week as part of my weekly review. It's a refresher for my mind so if I find myself at Wasabi I'm liable to remember that there was something I wanted to try and I can look it up. I don't necessarily read the entire list of "Things I Want" every week but I see that I have a list and I have a moment to think about if I want to get myself a gift. It's also handy to print and leave lying around the house round about birthday time!