In a large bowl, combine the finely chopped tomatoes, diced cucumber, and chopped red onion.
If using, add the finely chopped green chilies to the bowl. Stir in the fresh cilantro.
Drizzle the vegetable oil and lime juice (or lemon juice) over the salad. Toss gently to coat all the ingredients evenly.
Season the salad with salt and black pepper to taste. Mix well.
For best flavor, let the Kachumbari sit for about 15-30 minutes before serving to allow the flavors to meld together.
Enjoy your meal!