In a medium pot over medium heat, heat up 2 tablespoons of oil until the oil is shimmering, about 1 minute. Add the onion and cook, stirring occasionally, until softened, 5 to 6 minutes. When the onion has softened, stir in the garlic. After 1 minute, turn the heat to medium-high, mix in the diced tomatoes and cover. Cook until the tomatoes have broken down completely, stirring occasionally, about 5 minutes. When the tomatoes have disintegrated into a chunky sauce, add in the spinach, cilantro, xawaash, tomato paste, jalapeño, salt and 1 ½ cups of water. Lower heat to medium, cover, and cook the cagaar for 18 to 20 minutes, stirring occasionally. Discard the jalapeño, if you’d like, before serving. (Cagaar can last for 3 to 4 days, covered and refrigerated.)