Prep all the ingredients including removing the core of the head of lettuce and pulling off the leaves.
Heat a soup pot with cover over medium heat and melt butter. Add the lettuce, stir, cover and cook until wilted. This should take about 15 minutes but give it a stir occasionally so it doesn't burn. If you find the heat to high on your stove, turn it down a bit.
Add the cucumbers, scallions and potatoes. Stir to combine and reduce heat to low.
Add chicken broth to the pot to cover the vegetables. You want to add enough broth so the "veggies can float around, but don't drown".
Cover and cook for 20 - 30 minutes. If you are cooking on low and the pot is covered, there's very little chance you'll overcook this soup.
We used a hand blender to puree the soup but you can use a blender or food processor. When pureeing, if the soup looks to thick, add a little more chicken stock and cook a little longer on medium heat. If it looks too thin, continue cooking it down until it reaches the right consistency.
Taste and adjust seasonings with salt and pepper. I found it needed salt so I added a little and was sure to have salt and pepper shakers on the table.
You can serve this lettuce soup hot or cold making it a perfect year round soup. Enjoy