Mix the above ingredients for dressing – whisk in olive oil last. Set aside
Remove all woody ends from asparagus by snapping or cutting them off, place in a large bowl along with the lemon slices and toss with 1 Tbls of olive oil, salt and pepper.
Place on heated grill, turning frequently about 3-5 minutes.
When asparagus is cooked transfer to platter, drizzle with dressing and top with pistachios. Serve immediately.