Hot dang this soup is good. Not only because of it's Thai flavours, which are probably my favourite type, but because it has some depth to it, a little more robust flavour profile than a simple broth and coconut milk base. The good news it's it's dead simple to make and doesn't require a lot of ingredients. But I do think a high quality curry paste is a must - it absolutely sets the stage for the soup. Really, it's necessary for all the curry dishes you are making at home.
I don't have time, nor can be bothered to make a paste every time I make a simmering bowl of curry goodness. I make it at least one a week, if not more - especially during the winter. It's safe to say I'd be lost without these pastes. They are the best store bought ones I have found to date; they have strong fresh flavours that really sing and do remind me of my days in Thailand.
Heat the coconut oil or ghee in a large pan. Add the onions, and ginger and allow to cook for a few minutes, stirring occasionally. Add the garlic and give it a few more minutes. Stir in the curry paste, carrots and cauliflower and allow to cook for a few minutes. (You want the curry paste to toast a bit, but if it's getting too dry, add a splash of the broth). Then add all the broth, salt and pepper and bring to a slow simmer, allow to cook for 15-20 mins so the veg are soft. Using an immersion blender or a standard blender, blitz the mixture until it's smooth. Then add the coconut milk, soy sauce, fish sauce and lentils. Bring to a simmer for about 15 minutes. Taste and adjust seasoning as necessary. Pour into bowls and top with some additional coconut milk, sesame seeds or fried garlic as desired. Enjoy!