Heat vegetable oil in heavy large pot over medium-high heat. Add onions and cook until golden brown, stirring frequently, about 15 minutes. Add garlic and sauté 2 minutes. Add garam masala and next 4 ingredients; stir 1 minute. Add lentils; stir until coated. Add chicken stock. Bring soup to boil; reduce heat to a simmer until lentils are very tender, about 20 minutes. Discard bay leaves.
Use an immersion blender to puree soup until smooth. Return to pot. Stir in chicken, coconut milk, and lemon juice. Season to taste with salt and pepper.
Divide rice among bowls. Pour soup over. Garnish with cilantro and lemon wedges; serve