Add 1 onion, 3 cloves garlic, 2-inch knob ginger, and 1 serrano to a food processor. Pulse until everything is minced.
Heat 2 tablespoons oil in a large pot over medium-high. Add onion mixture and ½ teaspoon salt; cook until vegetables start to brown, about 8 minutes.
Meanwhile, add 5 ounces kale to food processor and pulse to roughly chop, about five 1-second pulses; set aside.
Stir 2 tablespoons curry powder into cooked onion mixture; cook 1 minute.
Add 6 cups broth and bring to a boil. Reduce heat to medium-low and stir in 1 cup lentils; cover and cook until lentils are nearly tender, about 12 minutes.
Stir in reserved chopped kale, 1 can coconut milk and 3 cups shredded chicken, return to a simmer and cook until greens are tender, about 5 minutes.
Stir in 2 tablespoons lime juice; season to taste with additional salt, pepper and lime juice.
Serve soup with lime zest, chopped peanuts and cilantro.