First, slice the eggplant, pretty thin, about 1/2-1/4 inch thick. Now lay on a paper towel or plate and sprinkle with the salt. Let sit for a minute while you mix the marinade.
In a large bowl or plastic container, make the marinade. Mix the citrus juices you are using. (I used fresh juices and squeezed them into a measuring cup), soy sauce, rice wine vinegar, sugar, garlic and ginger. Whisk to combine.
Now add the eggplant slices to the marinade. Stir to make sure all of the eggplant is in the marinade. Try to push all the slices into the liquid to ensure the eggplant absorbs the marinade.
Marinate for at least 3 hours, the longer the better, and I like to marinate the eggplant overnight. Stir the eggplant every once in a while so that it evenly absorbs the marinade.
Once you are ready to make the burgers, preheat the oven to 375 degrees. Spray a baking sheet with non stick spray, then remove the slices of eggplant from the marinade and place on the baking sheet.
Now roast the eggplant in the oven for 10-15 minutes until the eggplant is getting brown and firm. Then flip the eggplant and roast for another 10-15 minutes until the eggplant is completely brown and very firm.
While the eggplant is baking, you can make the wasabi mayo if you are using it. Just whisk together the mayo, wasabi powder and rice wine vinegar in a small mixing bowl.
Once the eggplant is done, put the wasabi mayo on a bun, then one or two slices of eggplant, then arugula and pickled veggies, then more mayo on the other bun, and place on top. Then you will definitely want to start eating!
Notes
You can use whatever citrus juice you want, I just recommend at least one sweet and one tart.