This is recipe with many virtues. Foremost, it hits the spot in this chilly season. For instance: before or after a night parade. It's also fast & easy. It's cheap too, perfect for these inflationary times. Finally, it's adaptable. The version presented here is pretty rustic, but you can give it the fancy Vichysoise treatment by pureeing the finished (and cooled!) soup and adding a little cream. If you use olive oil instead of butter and vegetable broth instead of chicken broth, the result will will be vegan. Or, go in the opposite direction and add a cup of chopped ham in the simmering stage. 

2 bunches green onions (about 8 ounces or so)
3-4 medium potatoes
1-2 cloves garlic
3 tablespoons butter
2 tablespoons flour
32 ounces chicken stock 
16 ounces water
1 teaspoon salt plus more to taste
Black pepper to taste

Clean and chop onions. Reserve a handful of the green tops to add at the end as garnish. Peel and dice potatoes. Finely chop the garlic.

Over medium heat, melt the butter in the soup pan. Add the onions and garlic and saute gently until softened and fragrant, about 5 minutes.

Add the flour and stir and cook, stirring, for a few minutes. The goal is not to develop color, just to cook the raw taste out of the flour. Slowly stir in the chicken stock and water.

Raise heat and bring to a boil. Add the potatoes. Add salt and pepper to taste. Reduce heat to a simmer.  It's done when the potatoes are tender, ~20 minutes or so.

Stir in chopped onion tops saved above.