If using dried black-eyed peas, soak them overnight and cook until tender. If using canned, rinse and drain them.
In a large skillet, heat oil over medium heat. Add cumin seeds and mustard seeds, letting them sizzle for a few seconds until fragrant.
Add the chopped onions to the skillet and sauté for 5-6 minutes or until golden brown. Add the curry leaves, garlic, and ginger. Saute for another minute until aromatic. Add the turmeric, coriander, red chili powder, and salt.
Add the green beans to the skillet and mix to coat them with the spices. Reduce the heat to medium-low, cover the skillet, and let the green beans cook for about 8-10 minutes, stirring occasionally, until they are tender but still have a bit of crunch.
Add the cooked black-eyed peas to the skillet. Cook for another 5-7 minutes, stirring occasionally, until the flavors meld together.
Turn off the heat and add the cilantro and lemon juice. Mix well and serve.
Notes
Cut the beans uniformly to enure they cook evenly.
Store any leftovers in the refrigerator for 4-5 days or in the freezer for up to two months.