Peel the sweet potatoes and pears then cut them into 2cm cubes. Finely chop the onion, carrot and celery.
Melt the butter and add the onions, carrots and celery - fry for 1 minute. Add the sweet potato and pear pieces, then the thyme. Sautee for 5 minutes under a lid.
Add the stock and paprika, bring to the boil, then simmer for 15 minutes, under cover.
Using a hand-held blender, pulse the soup until creamy. Add the maple syrup and lemon juice, then cook for 5 minutes until the soup has thickened to your liking.
Season with salt & pepper and add more lemon juice or maple syrup, if needed. Serve warm.