Combine vinegar, mustard, salt, pepper, and honey. Whisk oil into mixture in a continuous stream until fully emulsified.
Toss microgreens in just enough vinaigrette to coat; reserve remaining dressing. Arrange radish and cucumber slices in circular patterns on plates. Drizzle a swirl of dressing on radish swirls, then top with microgreens. Garnish with edible flowers and serve.