Wash the mitsuba and pick off the individual leaves. Pat completely dry with paper towel. Finely julienne the leaves, then spread out on paper towel.
Quickly wash the micro mitsuba leaves, place on paper towel and pat dry.
Pour the vegetable oil into a deep heavy-based saucepan, no more than one-third full, then heat to 170°C (325°F). Meanwhile, line a tray with dry paper towel.