Grate the cucumber with the skin on using the larger holes on a box grater. Transfer the grated cucumber to a sieve and use your hands to squeeze out the excess water.
Make the raita: Place the grated cucumber into a medium bowl. Add the yogurt, coriander, lemon juice, and salt to taste. Set aside.
Toast cumin seeds and cook aromatics: Heat the oil in a large skillet over medium-high heat. Toast the cumin seeds for 1 minute, or until fragrant. Add the onion and cook for about 5 minutes, or until softened. Add the garlic and cook for 1 minute more.
Sauté and season chickpeas: Add the chickpeas and stir to coat with the oil. Add the garam masala, turmeric, and coriander and cook for about 1 minute more, or until fragrant, stirring constantly.
Cook the kale: Add the tomato paste and cook for another minute, stirring constantly. Add ¼ cup water and mix to incorporate. Cook for 2 minutes more. Add the kale and cook for about 3 minutes, or until softened, adding more water as needed. Add lemon juice to taste and mix to incorporate.
For serving: Stir the raita. Serve with the chickpeas and a grain of your choice.