(By the way, if you want it guaranteed gluten free, leave out the lentils and check your vegan stock before use.)
800g fresh tomatoes
300g sweet potatoes
piece of peeled ginger about the size of your thumb
50g red lentils
2 tsp vegan powdered stock
salt to taste
Roughly chop the tomatoes, sweet potatoes and ginger. Place in a large pan. Rinse the lentils and add those too, along with the stock powder and water. Bring to the boil, then simmer for about 30 minutes until the sweet potato and lentils are completely soft and the tomatoes are starting to disintegrate.
Carefully blend until smooth, then sieve to get rid of all the most fibrous parts. At this point, you might want to add a bit more water if you like a runnier soup. Add salt to taste and then serve.