Put the chickpeas into a large bowl and cover them with cold water by a few inches. Cover the bowl with plastic wrap and let the chickpeas soak at room temperature for 8 hours or overnight.
Drain the chickpeas and peel each one by pinching and slipping off the skins. Discard the skins. (Alternatively, gently rub the chickpeas, in batches, between 2 kitchen towels to release the skins.) Rinse the chickpeas, then transfer them to a food processor. Add 3⁄4 cup water and purée the chickpeas until silky and smooth, about 3 minutes. Scrape down the inside of the food processor bowl with a rubber spatula and purée until very silky, about 3 minutes more. Set the chickpea purée aside.
Heat 3 tbsp. of the oil in a large pot over medium heat. Add the garlic and cook, stirring constantly, for 10 seconds. Add the onions and cook until soft, about 5 minutes. Add the tomatoes and continue cooking, stirring occasionally, until the mixture is reduced to a pulp, 5–6 minutes. Add the reserved chickpea purée and cook, stirring constantly, for 1 minute. Remove the pot from the heat and slowly whisk in 7 cups hot water until well combined and smooth. Return the pot to medium-low heat and simmer, whisking occasionally, until the mixture thickens and becomes satiny smooth, about 1 hour. Season with salt to taste, then ladle the porridge into a deep bowl and set aside to let firm up.
Meanwhile, put the chiles into a medium pot, cover with water, and bring to a boil. Boil gently until soft, about 15 minutes. Reserve 2 tbsp. of the cooking water and drain the chiles. Tear the chiles into small pieces. Transfer the chiles and reserved cooking water to a spice grinder or mini food processor and grind the mixture to a paste. Heat the remaining oil in a small skillet over medium heat. Add the chile purée and season with salt to taste. Cook the mixture, whisking constantly, until sizzling, about 1 minute. Drizzle the chile oil over the porridge and garnish with the cilantro sprigs.