Bring a pot of water to a boil.
Gently place the eggs in the boiling water and simmer for 4–6 minutes for a softly set yolk.
Immediately remove the eggs and transfer them to an ice bath to cool.
Peel the cooled eggs and set them aside.
In the same pot of boiling water, add the asparagus and cook for about 5 minutes until tender-crisp.
Add the peas for the final 1–2 minutes of cooking.
Immediately drain the vegetables and transfer them to an ice bath to halt the cooking process. Drain and set aside.
In a small bowl, combine and whisk the olive oil, lemon juice, and Dijon mustard until well mixed.
In a large serving bowl, combine the spinach, arugula, blanched asparagus, peas, radishes, and red onion.
Drizzle the dressing over the salad and toss gently until the ingredients are coated.
Divide the salad onto individual plates.
Halve the soft-boiled eggs and place two halves on top of each serving.
Garnish with fresh chopped herbs (chives or parsley) and serve immediately, with lemon wedges on the side if desired.