I had never eaten a tree tomato before visiting Rwanda, but I would happily eat one every day from now on if I could. Tree tomatoes taste tart and sweet, like hibiscus and tomato leaf and maybe pomegranate (though that could be the texture talking). In Rwanda, I also saw them referred to as a plums, 'Japanese fruits,' and prunes. A little online digging reveals they're also known as tamarillos and love fruits. Preeta says that in Malaysia, they eat them by biting off the top and sucking out the seedy insides. I consumed them mainly in juice form, but also as part of fruit salads, and in messy little piles, all by their tangy selves.
One of the best smells I experienced in Rwanda is related, though I don't believe it came solely from tree tomato trees. A powerful tomato-leaf-esque smell seemed to emanate from the hills themselves. I noticed it in particular when riding a bus with the window open or, even better, riding a moto and letting the breeze carry this scratchy green smell straight to me. In the evenings, there was sometimes a nightfire smell that mixed that same tomato leaf aroma with smoke and wood and a little bit of eucalyptus. Green and heady and rich enough to calm you no matter how fast the automobile carrying you is going.