In a large pot over medium heat, add the oil, onion, and ½ teaspoon salt. Cook for 5 minutes, or until softened, stirring occasionally.
Add the garlic, curry powder, and red pepper flakes (if using) and cook for 30 more seconds, stirring constantly. Stir in the carrots, cauliflower, lentils, and ½ teaspoon salt. Stir in the water and remaining ½ teaspoon salt, increase the heat to high and bring to a boil. Give it a stir, then reduce the heat to low and simmer, covered, for 25 minutes, stirring halfway through, or until lentils have broken down and carrots are very soft.
Transfer as much soup as can safely fit into your high-speed blender (it’s ok to leave some chunks/liquid behind) and blend on high until smooth, making sure to let the steam escape while blending (or use an immersion blender). Transfer back to the pot and stir in 3 tablespoons lemon juice and soy sauce or tamari.
Stir remaining 2 tablespoons lemon into the Sunflower Cream.
Serve the hot soup with a drizzle of sunflower cream and top with toasted sunflower seeds and herbs (if using).