Fill a large pot with about 2 inches of salted water and bring it to a boil.
Add the asparagus, cover, and steam until cooked to your liking, about 5 to 8 minutes depending on thickness. Drain.
Transfer the asparagus to a large bowl of ice water to cool, then drain again and gently pat dry. Set aside.
Combine lemon juice, vegetable broth, and white vinegar in a saucepan over medium heat. Cook until the sauce reduces by half.
Lower the heat to a simmer and whisk in the cream.
Add the sugar and whisk while adding the butter pats one at a time, letting each melt before adding the next.
Season with salt and pepper and simmer until the sauce begins to thicken.
Remove from heat and let stand for 2 minutes; taste and adjust seasoning.
Transfer the asparagus to a serving plate and drizzle the lemon butter sauce over it, or serve the sauce on the side.