In a large saucepan over high heat, combine the peas, water and ½ teaspoon of salt. Bring to a boil. Cover and simmer until the peas are tender, about 45 minutes.
Drain the peas, rinse with cold water, drain again, and transfer to a large bowl to cool.
Heat the oil in a heavy-bottomed frying pan or saucepan. Add the cumin seeds and cinnamon stick; let them sizzle for 10 seconds. Add the onions and garlic.
Stir over medium heat until soft and starting to brown, about 5 minutes. Add the mushroom and fry for 2 to 3 minutes. Add the tomatoes, ground coriander, cumin, turmeric, paprika and salt. Cover and cook over low heat for 10 minutes.
Add the cooked black-eyed peas to the tomato and mushroom mixture and season with salt to taste. Stir in the cilantro leaves and simmer, uncovered, for 10 minutes.