Instead of using oil I just saute the onions, garlic and celery in a little water. Enough water in the pan so they don't burn or stick to the bottom. If it starts to sizzle a bit much I add a little more water.
Next I add potatoes diced real small cover with water. These act as a thickener once they are cooked about 15 minutes later I mash them with an old time potato masher. You know the one that doesn't plug... if you don't have one of those just use a fork and smash them anyway you can.
Next add whatever vegetables you have in the fridge plus the beans, cover with water. Season to taste I use a lot of curry powder and enough cayenne to give it a bite. Salt (Celtic salt or sea salt if you have it) and pepper. Simmer until cooked about 15 minutes.