Heat butter in a large pot on a medium-high heat.
Add onion, garlic, ginger and jalapeno.
Cook, stirring, until browned for about 12 mins.
Lower the heat to medium.
Add coriander, cumin and turmeric powder and cook, until fragrant, stirring, for 45 secs.
Stir in the flour and cook further for 1 minute.
Pour in the broth and bring to a boil, while whisking constantly.
Add the lentils to the thickened broth.
Lower the heat and simmer, covered, until they become very tender.
Remove from the heat and allow to cool.
When the lentil mixture has cooled, stir in the chopped coriander leaves.
Working in batches, transfer the mixture to a blender and puree, until smooth or puree with an immersion blender.
Add the puree to the pot and reheat over medium heat.
Whisk the coconut milk, lemon juice, salt and season with pepper to taste.
Divide among warm soup bowls.
Garnish with the coriander sprigs.
:- Serve immediately with the lemon wedges.
:- If making the soup in advance, adjust it`s consistency when re-heating with water or broth, since it has a tendency to thicken as it sits.