For the asparagus, bring a pan of salted water to the boil. Add the asparagus to the water and blanch briefly.
Using tongs or a slotted spoon, remove the asparagus from the boiling water and place immediately into the iced water, then drain.
Heat a griddle pan until very hot. Drizzle olive oil over the asparagus and place onto the griddle. Cook, turning occasionally, until nicely marked and browned on all sides.
For the lemon and chive dressing, mix the juice of the lemon in a bowl with the olive oil, chopped shallot and chives and season with salt and freshly ground black pepper.
To serve, place six asparagus spears onto each of four plates. Dress with the lemon and chive vinaigrette.