In a large bowl, stir together the soy sauce, apple cider vinegar, extra virgin olive oil, maple syrup and liquid smoke.
Place the eggplant slices in a large plastic container and pour the soy-vinegar-oil marinade over them. Let marinate for 24 hours, rotating the eggplant once during the process. If the eggplant does not stay submerged, use something to weigh the slices down like pie weights or cans.
Preheat oven to 350 ?F. Remove the eggplant from the marinade and discard the remaining liquid. Lay the eggplant slices on a sheet tray lined with parchment paper making sure they don’t overlap. Cook the eggplant for 10-15 minutes. Set aside and let cool.