In a large pot, heat the olive oil over medium. Add the onion and carrots; season with salt and pepper. Cook, stirring occasionally, until the vegetables soften, about 4 minutes. Stir in the garlic, cumin and crushed red pepper. Cook, stirring, until fragrant, about 1 minute. Stir in the stock, chickpeas and tomatoes. In a blender, puree 2 cups of the mixture. Stir the puree into the stew, season and bring to a boil.
Reduce the heat to medium-low. Add the chicken and simmer, stirring occasionally, until the chicken is cooked through, about 5 minutes; season. Serve with the cilantro and lemon zest.