Preheat oven to 400°F (200°C).

Wash and trim the asparagus.

Toss the asparagus with olive oil, salt, and pepper.

Roast the asparagus for 15-20 minutes, or until tender.

In a large pot, sauté the onion and garlic until softened.

Add the roasted asparagus and vegetable broth to the pot.

Bring to a boil, then reduce heat and simmer for 10 minutes.

Use an immersion blender or transfer to a regular blender to blend until smooth.

Season with salt and pepper to taste.