Heat the olive oil in a saucepan over medium heat. Add the onion and fry until soft. Then add the chopped garlic which you quickly fry before adding the vegetable stock.
Bring stock to the boil and add the sweet potato cubes. These will take the longest to cook so they need to go first. Leave them boiling on a medium heat for around 5 minutes or more until softened.
Add broccoli and asparagus and simmer for another 5 minutes or so until all the vegetables are cooked.
Season to taste, with salt and pepper, as needed.
At the end blend with a hand blender until smooth. If you like some substance you can just blend it partially like I did. Serve with some Greek yoghurt on top, side salad and a toast.
Notes
If the soup feels too thick just add some water and if it doesn't feel thick enough add some flour mixed with water to thicken it up.