Preheat oven to 475°F. Wrap the eggplant in foil and place in the oven. Roast until collapsed and very tender, about 45 minutes. Remove the eggplant and loosen the foil. Slit it lengthwise to speed the cooling.
Combine the garlic, ginger, scallion, and Serrano pepper in the bowl of a small food processor fitter with blade attachment. Pulse to combine. Set aside. Combine the tamari, brown sugar, vinegar, sesame oil, and water. Stir to dissolve the sugar. Set aside.
Heat a wok over medium high heat. Add the canola oil and swirl to coat the pan. Add the reserved garlic-ginger mixture and red pepper flakes.
Cook, stirring constantly, until fragrant 45 to 60 seconds. Add the reserved sauce ingredients and eggplant.
Stir well to blend, and heat through. Taste and adjust for seasoning. Serve warm or cold. Keeps up to 5 days in an airtight container in the refrigerator.