Cut the eggplant into 2 or 3 logs depending on the length. Bring a pot of water to a boil. Add 2-3 tbsp of white vinegar to create a slightly acidic environment because anthocyanins are more stable at a lower pH. We don’t want the eggplant floating on top of the water while cooking, so use a tool to push them down. Why? Eggplants also contains a type of enzyme called polyphenol oxidase. The eggplant above the water, is a at a lower temperature, which means the enzyme is still active and it will oxidize the anthocyanins.
You don’t need to remember all this complicated science, the key here is to boil the eggplant with a little bit of vinegar and keep them under the water. It takes about 6-8 minutes over high heat. Of course, it depends on the thickness of your eggplant.
Remove them from the water and let them cool. The color does look fade now. But as it cools down, the purple will be more vivid. To show you a comparison, I boiled some eggplants without vinegar, and I didn’t push them down under the water. You can see a huge difference. This brown eggplant will still be delicious, but the anthocyanin is mostly destroyed.
Add a drizzle of vegetable oil to a sauce pot along with 10 cloves of finely chopped garlic, finely chopped; A few diced Thai bird eye chilies, 1 tbsp of chili flake. If you don’t eat spicy food, you can skip both thai birds eye chili and the chili flake. Stir over medium heat until the garlic is nice and fragrant. Add 1 tbsp of soy sauce, 1 tbsp of Chinese black vinegar, 1/2 tbsp of fish sauce, and 1/2 tsp of salt. Turn off the heat, toss in 1/4 cup of diced scallion. Mix well. If the sauce is a little bit dry, you can add a splash of water to mingle everything together. Remove from the heat.
Tear the eggplant into strips. Mix with the garlic sauce thoroughly. Enjoy!