In a large pot, heat the oil over medium. Add the onion, garlic and ginger; cook, stirring occasionally, until softened, about 4 minutes. Stir in the lentils, the stock and 2 cups water; bring to a boil over high.
When the mixture comes to a boil, add the chicken, reduce the heat to medium and cook until the chicken is cooked through, 5 to 7 minutes. Transfer the chicken to a plate. Let cool, then chop into bite-size pieces.
Stir the coconut milk, spices and 2 cups chard into the soup; season with salt and pepper. Cook over medium until the flavors meld, about 5 minutes. Stir in the chicken; divide among 4 bowls. Top with the remaining 1 cup chard.
