Heat the oil in a large stock over medium-high heat. (To save time, peel and dice the onion for the minute or so that the oil heats.) -Add the onion and saute for 5 minutes, or until cooked and translucent. Add the garilc and saute for an additional minute until fragrant. Stir in the masa harina and cook for an additional minute. -Pour in half of the chicken stock, and stir until completely combined. Add in the remainder of the chicken stock, and stir to combine. -Immediately add in the chicken, enchilada sauce, black beans, tomatoes, green chiles, salt and cumin, and stir until combined. -Continue stirring occasionally until the mixture reaches a simmer. -Reduce heat to medium-low and let it simmer for 3 minutes, stirring occasionally so that the soup does not stick to the bottom of the pan. -Then stir in the cheese, one handful at a time, until combined. Taste, and season the soup to taste with salt. Serve the soup warm with desired toppings.