Prep the vegetables: Rinse and dry the snap peas and radishes.
Trim the ends of the snap peas and slice them on a diagonal. Thinly slice the radishes into rounds or half-moons.
Make the dressing: In a small bowl, whisk together lemon juice, lemon zest, Dijon, honey, a pinch of salt, and a few grinds of pepper. Slowly whisk in the olive oil until the dressing is glossy and combined.
Add herbs and onion: Stir in the chopped herbs and green onion or chives.
Taste and adjust the seasoning—add more lemon for brightness, or a pinch more honey if it feels too sharp.
Assemble the salad: In a large bowl, combine the snap peas and radishes. Drizzle over about two-thirds of the dressing and toss gently to coat.
Add feta: Sprinkle in the crumbled feta and toss again very lightly so you keep some creamy chunks intact.
Finish and serve: Add the remaining dressing if needed and top with nuts or seeds for extra crunch. Serve right away for peak crispness.