Put the eggs in a medium saucepan and cover with cold water by 1 inch. Bring to a boil, then reduce the heat and gently simmer 10 minutes. Drain and rinse under cold water until cool; set aside.
Meanwhile, heat 1 tablespoon olive oil in a small skillet over medium heat. Add the chickpeas and season with salt and pepper. Cook, stirring, until the chickpeas are lightly browned, about 3 minutes. Add the pepitas and cook, stirring, until lightly toasted, about 2 minutes; let cool.
Make the dressing: Whisk the yogurt, 2 tablespoons water, the vinegar, chives and the remaining 1 tablespoon olive oil in a small bowl; season with salt and pepper.
Peel and roughly chop the hard-boiled eggs. Toss the greens, sprouts and radishes in a large bowl; season with salt and pepper. Top each serving of salad with the chickpeas and pepitas, eggs and sliced avocado. Drizzle with the dressing and top with more chives.