Sauté the onion in the oil, with salt, pepper and other spices. (Note - spice amounts are approximate. Adjust to taste/smell).
When the onions are translucent, add the stock and beans. Cover and simmer until the beans are just tender but not quite done.
Add chopped potato and yam. If necessary, add stock/water to cover. Simmer about 10 minutes.
Add the green beans or other vegetables. Simmer until potatoes are soft. Serve with rice or fresh bread.
The cook and prep time is highly dependent on what (or if) dried beans are used. Lentils and pre-soaked chick peas cook in about half an hour, other pre-soaked beans can take up to an hour and a half. But you can let the stew just simmer on the stove while you do other things, making the house smell wonderful. Or use canned beans. That works, too.