In late summer, one of my favorite things to make is Potato String Bean Pesto. The easy thing about it is those are the only three things you need. This time of year, you might be lucky and find a colorful range of string beans.
This is one of those loose recipes where I improvise in terms of proportions. A bunch of potatoes (new, not russet), a bunch of string beans, a bunch of pesto. Aside from having too little pesto, I can't imagine there are many wrong places to end up in terms of quantities. You can make your own pesto or be semi-lazy like me and buy some prepared — then you have a one pot–one colander meal.
What to do: Chop the potatoes and green beans to bite-size pieces. Bring a pot of water to boil and add just the potatoes for now. Cook them until a fork pierces easily. Then add the beans to the same pot, just for a minute or two. Their color will brighten, but they'll retain a crunchier texture. Drain, then return to the pot and mix in the pesto. Add salt to taste.
The key here is to make sure the potatoes are totally cooked before adding the beans, as you don't want to overcook the beans if you realize the potatoes need more time after you've already added the beans to the pot. Slightly overdone potatoes will just get creamier with the addition of the pesto, but overcooked string beans get dull and sad, though you'll probably still eat them if the pesto is good.
Leftovers can be eaten cold or room temperature.