Brinjals turn blackish, the moment you slice them; this is a natural process of oxidisation.
1. Always wash brinjals before slicing.
2. Add a tbsp. of milk to a bowl of water.
3. Add brinjal slices to the milk bowl, immediately after cutting.
4. Make sure the brinjal is completely submerged. Milk will help prevent the oxidisation process.
5. When ready to cook, take out the brinjal pieces, flatten them between your palms to get rid of excess moisture, and cook with them immediately.