Always roast or pan-fry purple asparagus if you want to keep the color. Boiling turns it green.
Preheat over to 400 F.
Prepare a baking sheet with parchment paper and set aside. Wash asparagus in warm water to remove any sand; dry and trim ends.
Place asparagus in a large plastic zip bag and add olive oil, shaking gently to coat.
Pour out on prepared baking sheet and roast for 15 minutes turning spears halfway through baking.
When done, remove from oven and squeeze lemon juice evenly over spears and sprinkle with fresh thyme.