I only make this sandwich in the summer when fresh tomatoes and fresh basil are available. I suppose that it could be made in other seasons but personally I won't touch a tomato unless I know it is fresh from the garden...the flavor is simply gone after summer. Likewise basil and other herbs. (By summer, I mean as long as the tomatoes last...It is October now and I am using the last of mine.) I usually use sharp cheddar cheese like Neal's yard. The combination of strong flavors (sharp cheddar, basil pesto and ham) keep the tastebuds busy.