First, prepare the asparagus. Wash the stalks thoroughly and snap off the tough, woody ends. Cut the top 1-2 inches (the delicate tips) from each stalk and set them aside for the garnish. Chop the remaining stalks into 1-inch pieces.

In a large pot or Dutch oven, melt the butter with the olive oil over medium heat. Add the chopped onion and a pinch of salt. Cook for 5-7 minutes, stirring occasionally, until the onion is soft and translucent.

Add the minced garlic and cook for another minute until fragrant, being careful not to let it burn.

Add the chopped asparagus stalks (not the tips) and the diced potato to the pot. Stir to coat with the aromatics. Pour in the vegetable broth, bring to a boil, then reduce the heat to a simmer.

Cover the pot and let it cook for 15-20 minutes, or until the asparagus and potato are very tender.

While the soup is simmering, bring a small pot of salted water to a boil. Add the reserved asparagus tips and blanch for 1-2 minutes until bright green and tender-crisp. Immediately drain and transfer them to a bowl of ice water to stop the cooking. Set aside.

Once the vegetables in the soup are tender, blend the soup until completely smooth. You can use an immersion blender directly in the pot or carefully transfer the soup in batches to a high-powered blender (ensure the lid is vented to let steam escape).

Return the blended soup to the pot over low heat. Stir in the heavy cream and fresh lemon juice. Heat gently but do not allow the soup to boil.

Taste the soup and season generously with salt and freshly cracked black pepper until the flavors are balanced.

Ladle the hot soup into bowls. Garnish with the blanched asparagus tips and optional toppings like a swirl of cream, a drizzle of olive oil, or fresh chives before serving.