Potato soaks up hot spices, so this dish is not that hot at all. To make the dish very mild either discard the jalapeno seeds, or use a green bell pepper or an anaheim pepper.
There is enough cilantro in this dish that it acts more like a green vegetable than a garnish. Substitute parsley if you don’t like cilantro - flat parsley works better, I think.
This dish is a good simple meal with whole wheat toast, or stuffed into a pita bread. Yogurt on the side makes a nice complement if you do dairy, but it isn’t necessary.
Saute the cumin seeds in the oil until they change color. Add the garlic and peppers, saute about 3 minutes more, then add the onions and saute another 3-4 min. Add the chopped potatoes, turn the flame very low and cook until potatoes are tender, about 10-15 min. Add water if needed to keep the potatoes from burning Add the black beans and heat through. Add the lemon or lime juice and cilantro, stir and serve.