Potato Soup with leek

2 tablespoons olive oil 1 lb leek , washed and sliced crosswise 1 large onion , finely chopped 2 lbs potatoes , peeled and cut into 1 inch cubes 4 cups beef[...]

1 1/2 lbs potatoes 2 tablespoons butter (or margarine or olive oil) 8 ounces bacon , chopped fine 1 cup chopped onion 1 cup sliced leek , green and white[...]