Turn on a griddle pan or cast iron grill.
Mix the miso, rice wine vinegar, oil, soy sauce, ginger and sesame seeds in a shallow dish.
Snap off the ends of the asparagus and discard. Place the asparagus in the marinade and coat them well.
Chop the spring onions.
Grill the asparagus, turning them occasionally, until charred and tender, brushing them with the marinade. This should take about 5 minutes.
Chop the spring onions and mix them with the remaining marinade.
Add these to the griddle pan for the last minute of cooking.
Transfer the asparagus and spring onion bits to a plate. Squeeze over some lime juice, then top with more sesame seeds.