Peel the eggplant and trim off the ends. Slice it into rounds about 1/2-inch thick. Line a baking sheet with parchment paper. Preheat oven to 400F.
In a large mixing bowl, combine all remaining ingredients and mix well. You should have a batter a little thicker than pancake batter. If it seems dry, add a splash of non-dairy milk.
Dip each eggplant slice into the batter and turn it to coat both sides and edges well. Holding the slice between two fingers, allow any excess batter to drip back into the bowl, and place the eggplant on the baking sheet. Repeat with as many slices as you can fit on the baking sheet, being careful that they do not touch. (If your baking sheet is small, you may need to make two batches; batter can thicken between batches, so add more liquid if necessary.)
Place in the oven. After 20 minutes, remove and gently turn each slice–you may have to hold the parchment paper and peel it from the eggplant. Replace and cook until outsides are brown but not burning, about 15 more minutes.
Serve hot on hoagie rolls or French bread with marinara sauce, lettuce, and tomato.
I used soy milk, which thickens with the addition of lemon juice. If you use another plant-based milk, you may need to add a little extra flour if the batter seems thin.Other flours should work, but I have only tested it at this time with brown rice flour. If you use a different flour, use your judgement about whether the batter needs to be thinned with extra milk or thickened with extra flour.Nutrition info is for eggplant only (not bread) and uses plain soy milk.