Heat 2 tbsp of olive oil in a large saucepan over medium heat. Add the chopped onions and garlic and sautee until the onions become transparent. Add 1 tsp turmeric and 1 1/2 tsp cumin and continue to mix and cook for another 2 minutes.
Add 1 additional tsp of olive oil and 1 1/2 cups of red lentils. Sautee for another minute stirring frequently so that lentils do not stick to the bottom of the pan.
Add 8 cups of vegetable stock, 1 medium potato peeled and cubed, 1 tsp paprika, 1/2 tsp black pepper and 1/8 tsp cayenne pepper (optional) and stir well. Let simmer for 30 minutes on medium-high heat stirring occasionally to ensure lentils do not settle and stick to the bottom.
Add in the juice of half a lemon and let simmer for another 2 minutes. Remove from heat and serve immediately. For a smoother soup texture remove from heat and carefully use a hand mixer/blender to blend the soup to a smooth texture. Serve immediately.
Vegetable broth can be swapped out for chicken broth for non-vegan or vegetarian diets.This soup can be stored in the fridge in a sealed container for up to 5 days. Freeze in individual portins for up to two months.