In a large pot, heat 2 tablespoons of oil over medium heat. Add the chopped onion, minced garlic, and freshly grated ginger. Cook these aromatics for about 5 minutes, until the onions are translucent.

Stir in 2 tablespoons of curry powder and cook for about 1 minute, stirring constantly to release the spices' aromas.

Add the rinsed red lentils, diced carrots, and chopped celery to the pot. Pour in 6 cups of vegetable broth and bring to a gentle boil.

Once boiling, reduce the heat and let the soup simmer for 20-25 minutes, stirring occasionally until lentils are tender.

For a creamier texture, use an immersion blender to purée the soup. Otherwise, transfer the soup to a countertop blender in batches.

Return the blended soup to the pot, add 1 can of coconut milk, and heat on low for an additional 5 minutes.

Ladle the soup into bowls and garnish with fresh spinach or cilantro if desired. Serve with crusty bread or over rice.