In a large dutch oven, add coconut oil and onions. Season with salt and pepper and cook 3-4 minutes. Then add the ginger, garlic and curry. Cook for 2 more minutes.
Add carrots and celery and cook 3 minutes. Add rinsed lentils, chicken stock, coconut milk and fish sauce. Bring to a low boil, then reduce heat and simmer for 25 minutes or until lentils are firm, but tender.
Finally add in the juice of 1 lime, and the spinach. Stir until spinach is wilted.
Top with cilantro and serve.