Wash the potatoes and cook covered for about 20 minutes. Peel, wash and chop the carrot. Clean, wash and cut the beans into pieces. Cover and cook in boiling salted water for about 8 minutes. Add peas and cook for about 3 minutes. Quench vegetables and let them cool down. Boil 3 eggs hard. Quench potatoes and eggs, peel and let them cool down
Mix egg yolk, lemon juice and salt. Stir the oil first drop by drop, then in a thin stream with the whisk of the hand mixer until the mayonnaise is creamy. Stir smooth with milk and season to taste
Dice the potatoes. Mix with vegetables and mayonnaise. Season everything with salt and pepper. Sprinkle with capers. Cut the eggs into eighths and arrange on the salad