When you live in a rural area, seasonal food means food that is in season in your area or in areas not too far from you. Living in a metropolitan area, where you have far greater access to food from all over the world, means that you see food that is in season someplace else on the globe. If I see a ton of cheap avocados, it means they're in season in Mexico or Puerto Rico, not Japan.
I'm not sure where most of the eggplants in Tokyo are coming from, but recent shopping trips would seem to indicate that they're in season somewhere. They're cheaper than usual and plentiful. To be honest, I'm not a serious eggplant fan, though I do enjoy them on occasion and in moderation. The only vegetarian lasagna I ever made (for a friend who didn't eat meat) was made with eggplant and it turned out extremely well.
This particular friend worked several "busy seasons" as a temp. at my former office and was one of the few people aside from myself who brought her own lunch. She likely had little choice because vegetarian options are painfully limited in Japan. Even when you ask and are told there's no meat in something, there is often some sort of meat in it. It seems that the question is often interpreted by the Japanese to mean, "are there big hunks of meat in it". They'll tell you there's no meat in the dish if it's something which has minced meat in small quantities or meat broth. The notion of being a vegetarian is relatively alien in Japan. I do several lessons where I talk about food with students and the idea of giving up meat sounds incredibly odd to them. Invariably, they see the option as being one based in health benefits rather than ecological ones or philosophical beliefs.

Getting back to this former co-worker though, it was often the case that I'd ask this particular friend what she'd brought for lunch and one day she said "aubergine stew". Since my second language was not French (it was Spanish) and Americans rarely say "aubergine", I asked what that was to which my (Australian) boss replied that it was what snooty people called "eggplant." He was just kidding, of course. She wasn't the least bit snooty, and fortunately was a good sport.
All those bags full of eggplants in the shops and some serious boredom with my usual lunchtime options inspired me to pick up a bag of small ones and try to put them to use. The result is something which is pretty simple and I mainly mention it in my blog to inspire others to consider enjoying the same thing, not because it's an uncommon combination.
This recipe has the virtue of being very cheap and fast. I had an hour before a lesson and watched the clock while I made it. The "hard part" takes about 6 minutes with a further 5 minutes or so in the toaster oven.
Open-face Eggplant Sandwich:
- 1 small eggplant
- 1 tbsp. all-purpose flour
- salt, pepper, garlic powder to taste (I used 1/2 tsp. salt, 1/4 tsp. pepper, and 1/2 tsp. garlic powder)
- olive oil as needed for frying
- 1/2 tomato (sliced)
- cheese as desired (Japanese natural "mixed" cheese is fine)
- French bread (or any other type of crusty bread)
While the eggplant is cooking, cut off a 5 inch section of French bread and slice it in half length-wise. Trim the top and bottom if necessary to make them sit flatter on the toaster oven tray. If the bread is tilted, the cheese will run off as it melts. Place the bread slices on the tray and put 4 or 5 cooked slices of eggplant on each piece. Top with slices of tomato. Season the tomato with salt then sprinkle the tops with cheese. It's tidier if you heap the cheese in the center so that it doesn't melt off the edges when you toast it. Toast (or broil) the sandwich until the cheese melts.
Note that it's very important to salt the tomato before adding the cheese or it'll taste rather bland and it doesn't work quite so well if you salt the cheese when the sandwich is done. Also, the topping for this sandwich is very soft so it's extremely important to use some good bread with heft and firmness.