Add the onion, garlic, asparagus, potatoes, chicken/vegetable stock, and salt and pepper to your slow cooker.
Cook on high for 4 hours or low for 8 hours.
Add the spinach to the soup- stir until wilted.
Add the dill.
Using an immersion blender, blend the soup until it reaches a thick and smooth consistency.
Stir in the lemon juice and adjust seasonings to taste.
Top with croutons and/or poached eggs, if desired.
To make on the stovetop, add onion, garlic, asparagus, potatoes, stock, and salt and pepper to a large pot and simmer for about 30 minutes, or until vegetables are very tender. Follow remaining instructions as described above.
Don't have an immersion blender? Use your regular blender or food processor to blend the soup in batches.
Have extra? Freeze it for up to 6 months in an airtight container.
The provided nutrition information does not include any added sodium from seasoning to taste, any optional ingredients, and it does not take brands into account. Feel free to calculate it yourself using this calculator or by adding the recipe to Yummly.