Boil potatoes until tender but still a firm center (for about 15 minutes). Whisk olive oil, vinegar, salt, and black pepper together in large bowl.
Drain potatoes and when cool enough to handle, cut in 1-inch cubes. Toss with vinaigrette dressing, until coated. Let cool.
When cool, add diced onion, celery, dill pickles, green chillies, coriander leaves, and black olives.
Mix. Mix mayonnaise with red chilli powder in small bowl and add to potato mixture.
All chopped eggs and toss gently. Chill for 1 to 2 hours before serving.