In a saucepan, melt the butter over medium heat. Add the chopped onion and garlic, sauté until translucent.

Add the asparagus pieces and diced potato, stirring for a few minutes.

Pour in the vegetable broth and bring to a boil. Reduce heat and simmer until the vegetables are tender, about 15 minutes.

Remove the saucepan from heat and let it cool slightly. Use a blender to puree the soup until smooth.

Return the soup to the saucepan and stir in the heavy cream, salt, pepper, and lemon juice.

Heat the soup gently over low heat until warmed through. Serve hot, garnished with additional asparagus tips if desired.