For the perfect hard-boiled eggs (no green yolks!) place the eggs in a small pot with enough water to cover the eggs by about 1 inch. Bring the water to a boil. When the water comes to a boil, let the eggs boil for 1 minute, then remove from heat, COVER, and let stand for 12 minutes. Peel when cooled. In a large pot, cover the potatoes with water and bring to a boil over high heat. When the water is boiling, add 1 tablespoon of salt and turn the heat down to keep the water at a gentle boil. Book the potatoes for about 10-15 minutes or until the potatoes are tender when pricked with a fork. Drain in a colander to cool the potatoes. While the potatoes are cooling, in a small bowl, whisk together the yogurt, mint, curry powder and cayenne pepper powder. In a large bowl, stir the onions, peas, celery and eggs together. Once the potatoes are cool, stir in the potatoes, vinegar, and yogurt mixture in with the peas, onions, celery and eggs. Stir gently with a wooden spoon. Salt and pepper to taste.